TOP234YN_技术文档

This product is not recommended for new designs.

TOP232-234

TOPSwitch-FXFamily

Design Flexible, EcoSmart, Integrated

Off-Line Switcher

Product Highlights

+

AC

IN

DC

Lower System Cost, High Design Flexibility

OUT

-

• Features eliminate or reduce cost of external components

• Fully integrated soft-start for minimum stress/overshoot

• Externally settable accurate current limit

• Wider duty cycle for more power, smaller input capacitor

• Line under-voltage (UV) detection: no turn off glitches

• Line overvoltage (OV) shutdown extends line surge limit

D

S

M

CONTROL

C

• Line feed-forward with maximum duty cycle (DC_MAX

reduction rejects ripple and limits DC_MAXat high line

)

TOPSwitch-FX

F

• Single resistor sets OV/UV thresholds, DC_MAXreduction

• Frequency jittering reduces EMI and EMI ﬁltering costs

• Regulates to zero load without dummy loading

• 132 kHz frequency reduces transformer/power supply size

• Half frequency option for video applications

PI-2503-062515

Figure 1. Typical Flyback Application.

• Hysteretic thermal shutdown for automatic recovery

• Large thermal hysteresis prevents PC board overheating

• Standard packages with omitted pins for large creepage

• Active-on and active-off remote ON/OFF capability

• Synchronizable to a lower frequency

OUTPUT POWER TABLE

Product³

230 VAC 1ꢀ5

Open

8ꢀ-26ꢀ VAC

Open

Adapter¹

Frame²

EcoSmart™– Energy Efﬁcient

• Cycle skipping reduces no-load consumption

• Reduced consumption in remote off mode

• Half frequency option for high efﬁciency standby

• Allows shutdown/wake-up via LAN/input port

TOP232P

TOP232G

TOP232Y

9 W

15 W

25 W

50 W

30 W

75 W

6.5 W

7 W

10 W

15 W

30 W

20 W

45 W

10 W

13 W

20 W

16 W

30 W

TOP233P

TOP233G

TOP233Y

TOP234P

TOP234G

TOP234Y

Description

9 W

TOPSwitch™-FX uses the proven TOPSwitch topology and

cost effectively integrates many new functions that reduce

system cost and, at the same time, improve design ﬂexibility,

performance and energy efﬁciency. Like TOPSwitch, the

high-voltage power MOSFET, PWM control, fault protection

and other control circuitry are all integrated onto a single

CMOS chip, but with two added terminals. The ﬁrst one is a

MULTI-FUNCTION (M) pin, which implements programmable

line OV/UV shutdown and line feed-forward/DC_MAXreduction

with line voltage. The same pin can be used instead to

externally set an accurate current limit. In either case, this pin

can also be used for remote ON/OFF or to synchronize the

oscillator to an external, lower frequency signal. The second

added terminal is the FREQUENCY (F) pin and is available only

in the Y package. This pin provides the half frequency option

when connected to CONTROL (C) instead of SOURCE (S).

The features on the new pins can be disabled by shorting

them to the SOURCE, which allows the device to operate in a

three terminal TOPSwitch mode, but with the following new

transparent features: soft-start, cycle skipping, 132 kHz

15 W

11 W

20 W

Table 1.

Notes:

1. Typical continuous power in a non-ventilated enclosed adapter measured at

50 ˚C ambient.

2. Maximum practical continuous power in an open frame design with adequate

heat sinking, measured at 50 ˚C ambient. See key applications section for

detailed conditions.

3. Packages: P: DIP-8B, G: SMD-8B, Y: TO-220-7B.

hysteretic thermal shutdown and larger creepage. In addition,

all critical parameters such as frequency, current limit, PWM

gain, etc. have tighter temperature and absolute tolerances

compared to the TOPSwitch-II family. Higher current limit

accuracy and larger DC_MAX, when combined with other

features allow for a 10% to 15% higher power capability on the

TOPSwitch-FX devices compared to equivalent TOPSwitch-II

devices for the same input/output conditions.

switching frequency, frequency jittering, wider DC_MAX

,

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June 2015

This Product is Covered by Patents and/or Pending Patent Applications.

TOP232-234

Section List

Pin Functional Description ....................................................................................................................................... 3

TOPSwitch-FX Family Functional Description ........................................................................................................ 4

CONTROL (C) Pin Operation.................................................................................................................................... 4

Oscillator and Switching Frequency.......................................................................................................................... 5

Pulse Width Modulator and Maximum Duty Cycle.................................................................................................... 5

Minimum Duty Cycle and Cycle Skipping ................................................................................................................. 6

Error Ampliﬁer .......................................................................................................................................................... 6

On-chip Current Limit with External Programability................................................................................................... 6

Line Undervoltage Detection (UV)............................................................................................................................. 6

Line Overvoltage Shutdown (OV).............................................................................................................................. 7

Line Feed-Forward with DC_MAXReduction ................................................................................................................ 7

Remote ON/OFF and Synchronization...................................................................................................................... 7

Soft-Start................................................................................................................................................................. 8

Shutdown/Auto-Restart ........................................................................................................................................... 8

Hysteretic Over-Temperature Protection................................................................................................................... 8

Bandgap Reference ................................................................................................................................................. 8

High-Voltage Bias Current Source............................................................................................................................ 8

Using FREQUENCY and MULTI-FUNCTION Pins .................................................................................................... 9

FREQUENCY (F) Pin Operation ................................................................................................................................ 9

MULTI-FUNCTION (M) Pin Operation........................................................................................................................ 9

Typical Uses of FREQUENCY (F) Pin ...................................................................................................................... 11

Typical Uses of MULTI-FUNCTION (M) Pin ............................................................................................................. 12

Application Examples ............................................................................................................................................. 14

A High Efﬁciency, 30 W, Universal Input Power Supply ........................................................................................... 14

35 W Multiple Output Power Supply....................................................................................................................... 15

17 W PC Standby Power Supply ........................................................................................................................... 16

Processor Controlled Supply Turn On/Off............................................................................................................... 17

Key Application Considerations .............................................................................................................................. 19

TOPSwitch-FX vs. TOPSwitch-ll............................................................................................................................. 19

TOPSwitch-FX Design Considerations ................................................................................................................... 20

TOPSwitch-FX Selection.................................................................................................................................. 20

Input Capacitor................................................................................................................................................ 20

Primary Clamp and Output Reﬂected Voltage V_OR.......................................................................................... 20

Output Diode................................................................................................................................................... 21

Soft-Start......................................................................................................................................................... 21

EMI ................................................................................................................................................................. 21

Transformer Design.......................................................................................................................................... 21

Standby Consumption..................................................................................................................................... 23

TOPSwitch-FX Layout Considerations.................................................................................................................... 23

Primary Side Connections ............................................................................................................................... 23

Y-Capacitor ..................................................................................................................................................... 23

Heat Sinking.................................................................................................................................................... 23

Quick Design Checklist .......................................................................................................................................... 23

Design Tools .......................................................................................................................................................... 23

Product Speciﬁcations and Test Conditions .......................................................................................................... 24

Typical Performance Characteristics ..................................................................................................................... 30

Package Outlines .................................................................................................................................................... 34

2

Rev. C 06/15

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TOP232-234

CONTROL (C)

DRAIN (D)

0

1

V

C

Z

INTERNAL

SUPPLY

C

SHUNT REGULATOR/

ERROR AMPLIFIER

+

-

SOFT START

5.8 V

4.8 V

-

5.8 V

+

INTERNAL UV

COMPARATOR

I

FB

V

I (LIMIT)

CURRENT

LIMIT

ADJUST

-

∏ 8

ON/OFF

+

SHUTDOWN/

AUTO-RESTART

V

+ V

BG

T

CURRENT LIMIT

COMPARATOR

MULTI-

FUNCTION (M)

HYSTERETIC

THERMAL

SHUTDOWN

V

BG

CONTROLLED

TURN-ON

GATE DRIVER

STOP

SOFT-

OV/UV

START

D

LINE

SENSE

MAX

DC

MAX

CLOCK

SAW

FREQUENCY (F)

(Y Package Only)

S

R

Q

HALF

FREQUENCY

-

LEADING

EDGE

BLANKING

+

OSCILLATOR WITH JITTER

PWM

COMPARATOR

R

E

SOURCE (S)

PI-2535-062615

Figure 2. Functional Block Diagram.

Pin Functional Description

DRAIN (D) Pin:

High-voltage power MOSFET drain output. The internal

start-up bias current is drawn from this pin through a switched

high-voltage current source. Internal current limit sense point

for drain current.

SOURCE (S) Pin:

Output MOSFET source connection for high-voltage power

return. Primary side control circuit common and reference

point.

Tab Internally

Connected to SOURCE Pin

CONTROL (C) Pin:

Error ampliﬁer and feedback current input pin for duty cycle

control. Internal shunt regulator connection to provide internal

bias current during normal operation. It is also used as the

connection point for the supply bypass and auto-restart/

compensation capacitor.

7

D

5

4

3

F

S

M

1

C

MULTI-FUNCTION (M) Pin:

Y Package (TO-220-7B)

Input pin for OV, UV, line feed-forward with DC_MAXreduction,

external set current limit, remote ON/OFF and synchronization.

A connection to SOURCE pin disables all functions on this pin

and makes TOPSwitch-FX operate in simple three terminal

mode (like TOPSwitch-II).

1

2

M

S

8

7

S

3

4

S

C

FREQUENCY (F) Pin: (Y package only)

5

D

Input pin for selecting switching frequency: 132 kHz if

connected to SOURCE pin and 66 kHz if connected to

CONTROL pin. The switching frequency is internally set for

132 kHz only operation in P and G packages.

P Package (DIP-8B)

G Package (SMD-8B)

PI-2501-031901

Figure 3. Pin Conﬁguration.

3

Rev. C 06/15

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TOP232-234

TOPSwitch-FX Family Functional Description

Auto-restart

I_CD1

Like TOPSwitch, TOPSwitch-FX is an integrated switched

mode power supply chip that converts a current at the control

input to a duty cycle at the open drain output of a high-voltage

power MOSFET. During normal operation the duty cycle of the

power MOSFET decreases linearly with increasing CONTROL

pin current as shown in Figure 4.

I_B

78

Slope = PWM Gain

47

I

= 140 µA

M

In addition to the three terminal TOPSwitch features, such as

the high-voltage start-up, the cycle-by-cycle current limiting,

loop compensation circuitry, auto-restart, thermal shutdown,

etc., the TOPSwitch-FX incorporates many additional functions

that reduce system cost, increase power supply performance

and design ﬂexibility. A patented high-voltage CMOS

technology allows both the high-voltage power MOSFET and

all the low voltage control circuitry to be cost effectively

integrated onto a single monolithic chip.

I

< I

M(DC)

M

I

= 190 µA

M

1.5

1.5 1.9

5.5 5.9

I_C(mA)

PI-2504-072799

Figure 4. Relationship of Duty Cycle to CONTROL Pin Current.

Two terminals, FREQUENCY (available only in Y package) and

MULTI-FUNCTION, have been added to implement some of

the new functions. These terminals can be connected to the

SOURCE pin to operate the TOPSwitch-FX in a TOPSwitch-

like three terminal mode. However, even in this three terminal

mode, the TOPSwitch-FX offers many new transparent

features that do not require any external components:

The FREQUENCY pin in the TO-220 package sets the

switching frequency to the default value of 132 kHz when

connected to SOURCE pin. A half frequency option can be

chosen by connecting this pin to CONTROL pin instead.

Leaving this pin open is not recommended.

CONTROL (C) Pin Operation

The CONTROL pin is a low impedance node that is capable of

receiving a combined supply and feedback current. During

normal operation, a shunt regulator is used to separate the

feedback signal from the supply current. CONTROL pin

voltage V_Cis the supply voltage for the control circuitry

including the MOSFET gate driver. An external bypass

capacitor closely connected between the CONTROL and

SOURCE pins is required to supply the instantaneous gate

drive current. The total amount of capacitance connected to

this pin also sets the auto-restart timing as well as control loop

compensation.

1. A fully integrated 10 ms soft-start reduces peak currents

and voltages during start-up and practically eliminates

output overshoot in most applications.

2. DC_MAXof 78% allows smaller input storage capacitor, lower

input voltage requirement and/or higher power capability.

3. Cycle skipping at minimum pulse width achieves regulation

and very low power consumption at no load.

4. Higher switching frequency of 132 kHz reduces the

transformer size with no noticeable impact on EMI or on

high line efﬁciency.

5. Frequency jittering reduces EMI.

6. Hysteretic over-temperature shutdown ensures automatic

recovery from thermal fault. Large hysteresis prevents circuit

board overheating.

7. Packages with omitted pins and lead forming provide large

DRAIN creepage distance.

When rectiﬁed DC high-voltage is applied to the DRAIN pin

during start-up, the MOSFET is initially off, and the CONTROL

pin capacitor is charged through a switched high-voltage

current source connected internally between the DRAIN and

CONTROL pins. When the CONTROL pin voltage V_Creaches

approximately 5.8 V, the control circuitry is activated and the

soft-start begins. The soft-start circuit gradually increases the

duty cycle of the MOSFET from zero to the maximum value

over approximately 10 ms. If no external feedback/supply

current is fed into the CONTROL pin by the end of the

soft-start, the high-voltage current source is turned off and the

CONTROL pin will start discharging in response to the supply

current drawn by the control circuitry. If the power supply is

designed properly, and no fault condition such as open loop or

shorted output exists, the feedback loop will close, providing

external CONTROL pin current, before the CONTROL pin

voltage has had a chance to discharge to the lower threshold

voltage of approximately 4.8 V (internal supply under-voltage

lockout threshold). When the externally fed current charges the

CONTROL pin to the shunt regulator voltage of 5.8 V, current

8. Tighter absolute tolerances and smaller temperature vari-

ations on switching frequency, current limit and PWM gain.

The MULTI-FUNCTION pin is usually used for line sensing by

connecting a resistor from this pin to the rectiﬁed DC high-

voltage bus to implement line over-voltage (OV)/under-voltage

(UV) and line feed-forward with DC_MAXreduction. In this mode,

the value of the resistor determines the OV/UV thresholds and

the DC_MAXis reduced linearly starting from a line voltage above

the under-voltage threshold. In high efﬁciency applications, this

pin can be used in the external current limit mode instead, to

reduce the current limit externally (to a value close to the

operating peak current), by connecting the pin to SOURCE

through a resistor. The same pin can also be used as a

remote ON/OFF and a synchronization input in both modes.

4

Rev. C 06/15

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TOP232-234

in excess of the consumption of the chip is shunted to

SOURCE through resistor R_Eas shown in Figure 2. This

current ﬂowing through R_Econtrols the duty cycle of the power

MOSFET to provide closed loop regulation. The shunt

regulator has a ﬁnite low output impedance Z_Cthat sets the

gain of the error ampliﬁer when used in a primary feedback

conﬁguration. The dynamic impedance Z_Cof the CONTROL

pin together with the external CONTROL pin capacitance sets

the dominant pole for the control loop.

sawtooth waveform for the pulse width modulator. The

oscillator sets the pulse width modulator/current limit latch at

the beginning of each cycle.

The nominal switching frequency of 132 kHz was chosen to

minimize transformer size while keeping the fundamental EMI

frequency below 150 kHz. The FREQUENCY pin (available

only in TO-220 package), when shorted to the CONTROL pin,

lowers the switching frequency to 66 kHz (half frequency)

which may be preferable in some cases such as noise

sensitive video applications or a high efﬁciency standby mode.

Otherwise, the FREQUENCY pin should be connected to the

SOURCE pin for the default 132 kHz. Trimming of the current

reference improves oscillator frequency accuracy.

When a fault condition such as an open loop or shorted output

prevents the ﬂow of an external current into the CONTROL pin,

the capacitor on the CONTROL pin discharges towards 4.8 V.

At 4.8 V auto-restart is activated which turns the output MOSFET

off and puts the control circuitry in a low current standby

mode. The high-voltage current source turns on and charges

the external capacitance again. A hysteretic internal supply

under-voltage comparator keeps V_Cwithin a window of

typically 4.8 to 5.8 V by turning the high-voltage current source

on and off as shown in Figure 5. The auto-restart circuit has a

divide-by-8 counter which prevents the output MOSFET from

turning on again until eight discharge/charge cycles have

elapsed. This is accomplished by enabling the output MOSFET

only when the divide-by-8 counter reaches full count (S7). The

counter effectively limits TOPSwitch-FX power dissipation by

reducing the auto-restart duty cycle to typically 4%. Auto-

restart mode continues until output voltage regulation is again

achieved through closure of the feedback loop.

To further reduce the EMI level, the switching frequency is

jittered (frequency modulated) by approximately 4 kHz at

250 Hz (typical) rate as shown in Figure 6. Figure 28 shows

the typical improvement of EMI measurements with frequency

jitter.

Pulse Width Modulator and Maximum Duty Cycle

The pulse width modulator implements voltage mode control

by driving the output MOSFET with a duty cycle inversely

proportional to the current into the CONTROL pin that is in

excess of the internal supply current of the chip (see Figure 4).

The excess current is the feedback error signal that appears

across R_E(see Figure 2). This signal is ﬁltered by an RC

network with a typical corner frequency of 7 kHz to reduce the

effect of switching noise in the chip supply current generated

Oscillator and Switching Frequency

The internal oscillator linearly charges and discharges an

internal capacitance between two voltage levels to create a

V_UV

V_LINE

0 V

S0

S7

S1

S2

S6

S7 S0

S1

S2

S6

S7

S1 S2

S6

S7

5.8 V

4.8 V

V_C

0 V

V_DRAIN

0 V

V_OUT

0 V

1

2

3

2

4

Note: S0 through S7 are the output states of the auto-restart counter

PI-2545-082299

Figure 5. Typical Waveforms for (1) Power Up (2) Normal Operation (3) Auto-restart (4) Power Down .

ꢀ

Rev. C 06/15

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TOP232-234

by the MOSFET gate driver. The ﬁltered error signal is

compared with the internal oscillator sawtooth waveform to

generate the duty cycle waveform. As the control current

increases, the duty cycle decreases. A clock signal from the

oscillator sets a latch which turns on the output MOSFET. The

pulse width modulator resets the latch, turning off the output

MOSFET. Note that a minimum current must be driven into

the CONTROL pin before the duty cycle begins to change.

136 kHz

Switching

Frequency

128 kHz

4 ms

V_DRAIN

The maximum duty cycle, DC_MAX, is set at a default maximum

value of 78% (typical). However, by connecting the MULTI-

FUNCTION pin to the rectiﬁed DC high-voltage bus through a

resistor with appropriate value, the maximum duty cycle can

be made to decrease from 78% to 38% (typical) as shown in

Figure 8 when input line voltage increases (see line feed-

forward with DC_MAXreduction).

Time

Figure 6. Switching Frequency Jitter.

internally. However, with a resistor connected between

MULTI-FUNCTION pin and SOURCE pin, current limit can be

programmed externally to a lower level between 40% and

100% of the default current limit. Please refer to the graphs in

the typical performance characteristics section for the

selection of the resistor value. By setting current limit low, a

TOPSwitch-FX that is bigger than necessary for the power

required can be used to take advantage of the lower R_DS(ON)for

higher efﬁciency. With a second resistor connected between

the MULTI-FUNCTION pin and the rectiﬁed DC high-voltage

bus providing a small amount of feed-forward current, a true

power limiting operation against line variation can be

implemented. When using an RCD clamp, this feed-forward

technique reduces maximum clamp voltage at high line

allowing for higher reﬂected voltage designs. The current limit

comparator threshold voltage is temperature compensated to

minimize the variation of the current limit due to temperature

related changes in R_DS(ON)of the output MOSFET.

Minimum Duty Cycle and Cycle Skipping

To maintain power supply output regulation, the pulse width

modulator reduces duty cycle as the load at the power supply

output decreases. This reduction in duty cycle is proportional

to the current ﬂowing into the CONTROL pin. As the CONTROL

pin current increases, the duty cycle reduces linearly towards

a minimum value speciﬁed as minimum duty cycle, DC_MIN

.

After reaching DC_MIN, if CONTROL pin current is increased

further by approximately 0.4 mA, the pulse width modulator

will force the duty cycle from DC_MINto zero in a discrete step

(refer to Figure 4). This feature allows a power supply to

operate in a cycle skipping mode when the load at its output

consumes less power than the power that TOPSwitch-FX

delivers at minimum duty cycle, DC_MIN. No additional control is

needed for the transition between normal operation and cycle

skipping. As the load increases or decreases, the power

supply automatically switches between normal operation and

cycle skipping mode as necessary.

The leading edge blanking circuit inhibits the current limit

comparator for a short time after the output MOSFET is turned

on. The leading edge blanking time has been set so that, if a

power supply is designed properly, current spikes caused by

primary-side capacitances and secondary-side rectiﬁer

reverse recovery time will not cause premature termination of

the switching pulse.

Cycle skipping may be avoided, if so desired, by connecting a

minimum load at the power supply output such that the duty

cycle remains at a level higher than DC_MINat all times.

Error Ampliﬁer

The shunt regulator can also perform the function of an error

ampliﬁer in primary feedback applications. The shunt regulator

voltage is accurately derived from a temperature-compensated

bandgap reference. The gain of the error ampliﬁer is set by the

CONTROL pin dynamic impedance. The CONTROL pin

clamps external circuit signals to the V_Cvoltage level. The

CONTROL pin current in excess of the supply current is

separated by the shunt regulator and ﬂows through R_Eas a

voltage error signal.

The current limit can be lower for a short period after the

leading edge blanking time as shown in Figure 33. This is due

to dynamic characteristics of the MOSFET. To avoid triggering

the current limit in normal operation, the drain current

waveform should stay within the envelope shown.

Line Undervoltage Detection (UV)

At power up, UV keeps TOPSwitch-FX off until the input line

voltage reaches the undervoltage threshold. At power down,

UV prevents auto-restart attempts after the output goes out of

regulation. This eliminates power down glitches caused by

the slow discharge of input storage capacitor present in

applications such as standby supplies. A single resistor

connected from the MULTI-FUNCTION pin to the rectiﬁed DC

high-voltage bus sets UV threshold during power up. Once the

power supply is successfully turned on, UV is disabled to

On-Chip Current Limit with External Programmability

The cycle-by-cycle peak drain current limit circuit uses the

output MOSFET ON-resistance as a sense resistor. A current

limit comparator compares the output MOSFET on-state drain

to source voltage, V_DS(ON)with a threshold voltage. High drain

current causes V_DS(ON)to exceed the threshold voltage and

turns the output MOSFET off until the start of the next clock

cycle. The default current limit of TOPSwitch-FX is preset

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Rev. C 06/15

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TOP232-234

allow extended input voltage operating range. Input voltage is

not checked again until the power supply loses regulation and

attempts another turn-on. This is accomplished by enabling

the UV comparator only when the divide-by-8 counter used in

auto-restart reaches full count (S7) which is also the state that

the counter is reset to at power up (see Figure 5). The UV

feature can be disabled independent of OV feature as shown

in Figure 16.

Remote ON/OFF and Synchronization

TOPSwitch-FX can be turned on or off by controlling the

current into or out from the MULTI-FUNCTION pin (see Figure

8). This allows easy implementation of remote ON/OFF control

of TOPSwitch-FX in several different ways. A transistor or an

optocoupler output connected between the MULTI-FUNCTION

pin and the SOURCE pin implements this function with

“active-on” (Figure 19) while a transistor or an optocoupler

output connected between the MULTI-FUNCTION pin and the

CONTROL pin implements the function with “active-off”

(Figure 20).

Line Overvoltage Shutdown (OV)

The same resistor used for UV also sets an overvoltage

threshold which, once exceeded, will force TOPSwitch-FX

output into off-state. The ratio of OV and UV thresholds is

preset at 4.5 as can be seen in Figure 8. This feature turns off

the TOPSwitch-FX power MOSFET when the rectiﬁed DC

high-voltage exceeds the OV threshold. When the MOSFET is

off, the rectiﬁed DC high-voltage surge capability is increased

to the voltage rating of the MOSFET (700 V), due to the

absence of the reﬂected voltage and leakage spikes on the

drain. Small amount of hysteresis is provided on the OV

threshold to prevent noise triggering. The OV feature can be

disabled independent of UV feature as shown in Figure 15.

When a signal is received at the MULTI-FUNCTION pin to

disable the output through any of the MULTI-FUNCTION pin

functions such as OV, UV and remote ON/OFF, TOPSwitch-FX

always completes its current switching cycle as illustrated in

Figure 7 before the output is forced off. The internal oscillator

is stopped slightly before the end of the current cycle and

stays there as long as the disable signal exists. When the

signal at the MULTI-FUNCTION pin changes state from disable

to enable, the internal oscillator starts the next switching cycle.

This approach allows the use of this pin to synchronize

TOPSwitch-FX to any external signal with a frequency lower

than its internal switching frequency.

Line Feed-Forward with DC_MAXReduction

The same resistor used for UV and OV also implements line

voltage feed-forward which minimizes output line ripple and

reduces power supply output sensitivity to line transients. This

feed-forward operation is illustrated in Figure 4 by the different

values of I_M. Note that for the same CONTROL pin current,

higher line voltage results in smaller operating duty cycle. As

an added safety measure, the maximum duty cycle DC_MAXis

also reduced from 78% (typical) at a voltage slightly higher

than the UV threshold to 38% (typical) at the OV threshold (see

Figures 4, 8). DC_MAXof 38% at the OV threshold was chosen

to ensure that the power capability of the TOPSwitch-FX is not

restricted by this feature under normal operation.

As seen above, the remote ON/OFF feature allows the

TOPSwitch-FX to be turned on and off instantly, on a cycle-by-

cycle basis, with very little delay. However, remote ON/OFF

can also be used as a standby or power switch to turn off the

TOPSwitch-FX and keep it in a very low power consumption

state for indeﬁnitely long periods. If the TOPSwitch-FX is held

in remote off state for long enough time to allow the CONTROL

pin to dishcharge to the internal supply undervoltage threshold

of 4.8 V (approximately 32 ms for a 47 µF CONTROL pin

capacitance), the CONTROL pin goes into the hysteretic mode

of regulation. In this mode, the CONTROL pin goes through

Time

Figure 7. Synchronization Timing Diagram.

7

Rev. C 06/15

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TOP232-234

alternate charge and discharge cycles between 4.8 V and

5.8 V (see CONTROL pin operation section above) and runs

entirely off the high-voltage DC input, but with very low power

consumption (160 mW typical at 230 VAC with M pin open).

When the TOPSwitch-FX is remotely turned on after entering

this mode, it will initiate a normal start-up sequence with

soft-start the next time the CONTROL pin reaches 5.8 V. In the

worst case, the delay from remote on to start-up can be equal

to the full discharge/charge cycle time of the CONTROL pin,

which is approximately 125 ms for a 47 µF CONTROL pin

capacitor. This reduced consumption remote off mode can

eliminate expensive and unreliable in-line mechanical switches.

It also allows for microprocessor controlled turn-on and

turn-off sequences that may be required in certain applications

such as inkjet and laser printers. See Figure 27 under

application examples for more information.

restart mode described above. When the fault condition is

removed, the power supply output becomes regulated, V_C

regulation returns to shunt mode, and normal operation of the

power supply resumes.

Hysteretic Over-Temperature Protection

Temperature protection is provided by a precision analog

circuit that turns the output MOSFET off when the junction

temperature exceeds the thermal shutdown temperature

(135 ˚C typical). When the junction temperature cools to below

the hysteretic temperature, normal operation resumes. A large

hysteresis of 70 ˚C (typical) is provided to prevent overheating

of the PC board due to a repeating fault condition. V_Cis

regulated in hysteretic mode and a 4.8 V to 5.8 V (typical)

sawtooth waveform is present on the CONTROL pin when the

power supply is turned off.

Bandgap Reference

Soft-Start

All critical TOPSwitch-FX internal voltages are derived from a

temperature-compensated bandgap reference. This reference

is also used to generate a temperature-compensated current

reference which is trimmed to accurately set the switching

frequency, MOSFET gate drive current, current limit, and the

line OV/UV thresholds. TOPSwitch-FX has improved circuitry

to maintain all of the above critical parameters within very tight

absolute and temperature tolerances.

An on-chip soft-start function is activated at start-up with a

duration of 10 ms (typical). Maximum duty cycle starts from

zero and linearly increases to the default maximum of 78% at

the end of the 10 ms duration. In addition to start-up, soft-

start is also activated at each restart attempt during auto-

restart and when restarting after being in hysteretic regulation

of CONTROL pin voltage (V_C), due to remote off or thermal

shutdown conditions. This effectively minimizes current and

voltage stresses on the output MOSFET, the clamp circuit and

the output rectiﬁer, during start-up. This feature also helps

minimize output overshoot and prevents saturation of the

transformer during start-up.

High-Voltage Bias Current Source

This current source biases TOPSwitch-FX from the DRAIN pin

and charges the CONTROL pin external capacitance during

start-up or hysteretic operation. Hysteretic operation occurs

during auto-restart, remote off and over-temperature shutdown.

In this mode of operation, the current source is switched on

and off with an effective duty cycle of approximately 35%.

This duty cycle is determined by the ratio of CONTROL pin

charge (I_C) and discharge currents (I_CD1and I_CD2). This current

source is turned off during normal operation when the output

MOSFET is switching.

Shutdown/Auto-Restart

To minimize TOPSwitch-FX power dissipation under fault

conditions, the shutdown/auto-restart circuit turns the power

supply on and off at an auto-restart duty cycle of typically 4%

if an out of regulation condition persists. Loss of regulation

interrupts the external current into the CONTROL pin. V_C

regulation changes from shunt mode to the hysteretic auto-

8

Rev. C 06/15

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TOP232-234

connecting a resistor from this pin to the rectiﬁed DC high-

voltage bus to implement OV, UV and DC_MAXreduction with

line voltage functions. In this mode, the value of the resistor

determines the line OV/UV thresholds, and the DC_MAXis

reduced linearly with rectiﬁed DC high-voltage starting from

just above the UV threshold. In high efﬁciency applications

this pin can be used in the external current limit mode instead,

to reduce the current limit externally to a value close to the

operating peak current, by connecting the pin to the SOURCE

pin through a resistor. The same pin can also be used as a

remote on/off and a synchronization input in both modes.

Please refer to Table 2 for possible combinations of the

functions with example circuits shown in Figure 13 through

Figure 23. A description of speciﬁc functions in terms of the

MULTI-FUNCTION pin I/V characteristic is shown in Figure 8.

The horizontal axis represents MULTI-FUNCTION pin current

with positive polarity indicating currents ﬂowing into the pin.

The meaning of the vertical axes varies with functions. For

those that control the on/off states of the output such as UV,

OV and remote ON/OFF, the vertical axis represents the enable/

disable states of the output. UV triggers at I_UV(+50 µA typical)

and OV triggers at I_OV(+225 µA typical). Between +50 µA and

+225 µA, the output is enabled. For external current limit and

line feed-forward with DC_MAXreduction, the vertical axis

represents the magnitude of the I_LIMITand DC_MAX. Line feed-

forward with DC_MAXreduction lowers maximum duty cycle

from 78% at I_M(DC)(+90 µA typical) to 38% at I_OV(+225 µA).

External current limit is available only with negative MULTI-

FUNCTION pin current. Please see graphs in the typical

performance characteristics section for the current limit program-

ming range and the selection of appropriate resistor value.

Using FREQUENCY and MULTI-FUNCTIONAL Pins

FREQUENCY (F) Pin Operation

The FREQUENCY pin is a digital input pin available in TO-220

package only. Shorting the FREQUENCY pin to SOURCE pin

selects the nominal switching frequency of 132 kHz (Figure 10)

which is suited for most applications. For other cases that

may beneﬁt from lower switching frequency such as noise

sensitive video applications, a 66 kHz switching frequency (half

frequency) can be selected by shorting the FREQUENCY pin

to the CONTROL pin (Figure 11). In addition, an example

circuit shown in Figure 12 may be used to lower the switching

frequency from 132 kHz in normal operation to 66 kHz in

standby mode for very low standby power consumption.

MULTI-FUNCTION (M) Pin Operation

When current is fed into the MULTI-FUNCTION pin, it works as

a voltage source of approximately 2.6 V up to a maximum

current of +400 µA (typical). At +400 µA, this pin turns into a

constant current sink. When current is drawn out of the

MULTI-FUNCTION pin, it works as a voltage source of

approximately 1.32 V up to a maximum current of –240 µA

(typical). At –240 µA, it turns into a constant current source.

Refer to Figure 9.

There are a total of ﬁve functions available through the use of

the MULTI-FUNCTION pin: OV, UV, line feed-forward with

DC_MAXreduction, external current limit and remote ON/OFF. A

short circuit between the MULTI-FUNCTION pin and SOURCE

pin disables all ﬁve functions and forces TOPSwitch-FX to

operate in a simple three terminal mode like TOPSwitch-II. The

MULTI-FUNCTION pin is typically used for line sensing by

MULTI-FUNCTION PIN TABLE*

13

14

15

16

17

18

19

20

21

22

23

Figure Number ꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀ

4

Three Terminal Operation

Undervoltage

4

Overvoltage

4

Line Feed-forward (DC_MAX

)

Line Feed-forward (I_LIMIT

External Current Limit

Remote ON/OFF

)

4ꢀ

4

ꢀ

4

*This table is only a partial list of many MULTI-FUNCTION pin conﬁgurations that are possible.

Table 2. Typical MULTI-FUNCTION Pin Conﬁgurations.

9

Rev. C 06/15

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TOP232-234

I_REM(N)

I_UV

I_OV

(Enabled)

Output

MOSFET

Switching

(Disabled)

Disabled when supply

output goes out of

regulation

I_M

I_LIMIT(Default)

Current

Limit

I_M

DC_MAX(78.5%)

Maximum

Duty Cycle

I_M

V_BG+ V_TP

MULTI-

FUNCTION

Pin Voltage

V_BG

I_M

-250

-200

-150

-100

-50

0

50

100

150

200

250

300

350

400

MULTI-FUNCTION Pin Current (µA)

Note: This figure provides idealized functional characteristics of the MULTI-FUNCTION pin with typical performance values.

Please refer to the parametric table and typical performance characteristics sections of the data sheet for measured data.

PI-2524-081999

Figure 8. MULTI-FUNCTION Pin Characteristics.

CONTROL Pin

TOPSwitch-FX

240 µA

(Negative Current Sense - ON/OFF,

Current Limit Adjustment)

V_BG+ V_T

MULTI-FUNCTION Pin

V_BG

(Positive Current Sense - Undervoltage,

Overvoltage, Maximum Duty

Cycle Reduction)

400 µA

PI-2548-062515

Figure 9. MULTI-FUNCTION Pin Input Simpliﬁed Schematic.

10

Rev. C 06/15

www.power.com

TOP232-234

Typical Uses of FREQUENCY (F) Pin

+

DC

Input

Voltage

DC

Input

D

S

D

CONTROL

Voltage

C

F

S

F

-

PI-2506-081199

PI-2505-081199

Figure 11. Half Frequency Operation (66 kHz).

Figure 10. Full Frequency Operation (132 kHz).

+

Q_Scan be an optocoupler output.

DC

Input

Voltage

D

S

CONTROL

C

STANDBY

F

47 kΩ

Q_S

1 nF

20 kΩ

R_HF

-

PI-2507-040401

Figure 12. Half Frequency Standby Mode (For High Standby Efﬁciency).

11

Rev. C 06/15

www.power.com

TOP232-234

Typical Uses of MULTI-FUNCTION (M) Pin

+

V_UV= I_UVx R_LS

V_OV= I_OVx R_LS

For R_LS= 2 MΩ

V_UV= 100 VDC

V_OV= 450 VDC

R_LS

2 MΩ

DC

Input

DC

Input

Voltage

DC_MAX@100 VDC = 78%

DC_MAX@375 VDC = 47%

D

S

M

D

S

M

CONTROL

C

-

PI-2508-081199

PI-2509-040401

Figure 13. Three Terminal Operation (MULTI-FUNCTION Features Disabled.

FREQUENCY Pin Tied to SOURCE or CONTROL Pin).

Figure 14. Line Sensing for Undervoltage, Overvoltage and Maximum Duty

Cycle Reduction.

+

V_UV= R_LSx I_UV

2 MΩ

V_OV= I_OVx R_LS

2 MΩ

For Value Shown

V_UV= 100 VDC

For Values Shown

V_OV= 450 VDC

R_LS

DC

Input

DC

Input

22 kΩ

30 kΩ

IN4148

Voltage

D

S

M

D

S

M

CONTROL

C

6.2 V

-

PI-2510-040401

PI-2516-040401

Figure 15. Line Sensing for Undervoltage Only (Overvoltage Disabled).

Figure 16. Line Sensing for Overvoltage Only (Undervoltage Disabled).

+

For R_IL= 12 kΩ

I_LIMIT= 90% @ 100 VDC

I_LIMIT= 67%

I_LIMIT

=

55% @ 300 VDC

R_LS

2.5 MΩ

For R_IL= 25 kΩ

I_LIMIT= 40%

DC

Input

Voltage

DC

See graph for other

Input

resistor values (R_IL)

Voltage

D

S

M

D

M

CONTROL

R_IL

6 kΩ

C

R_IL

S

-

PI-2518-040401

PI-2517-040401

Figure 18. Current Limit Reduction with Line Voltage.

Figure 17. Externally Set Current Limit.

12

Rev. C 06/15

www.power.com

TOP232-234

Typical Uses of MULTI-FUNCTION (M) Pin (cont.)

+

Q_Rcan be an optocoupler

output or can be replaced

by a manual switch.

Q_Rcan be an optocoupler

output or can be replaced by

a manual switch.

Q_R

DC

Input

Voltage

DC

Input

Voltage

ON/OFF

R_MC

47 kΩ

45 kΩ

D

S

M

D

M

CONTROL

C

Q_R

C

ON/OFF

47 kΩ

-

S

-

PI-2519-040401

PI-2522-040401

Figure 19. Active-on (Fail Safe) Remote ON/OFF.

Figure 20. Active-Off Remote ON/OFF.

+

Q_Rcan be an optocoupler

output or can be replaced

by a manual switch.

Q_Rcan be an optocoupler

output or can be replaced

by a manual switch.

Q_R

For R_IL= 12 kΩ

I_LIMIT= 67 %

ON/OFF

DC

Input

DC

Input

Voltage

47 kΩ

For R_IL= 25 kΩ

I_LIMIT= 40 %

Voltage

R_MC

24 kΩ

R_MC= 2R_IL

D

S

M

R_IL

Q_R

D

S

M

CONTROL

C

R_IL

C

12 kΩ

ON/OFF

47 kΩ

-

PI-2520-040401

PI-2521-040401

Figure 21. Active-on Remote ON/OFF with Externally Set Current Limit.

Figure 22. Active-off Remote ON/OFF with Externally Set Current Limit.

Q_Rcan be an optocoupler

output or can be replaced

by a manual switch.

+

R_LS

2 MΩ

Q_R

DC

Input

ON/OFF

47 kΩ

For R_LS= 2 MΩ

Voltage

D

M

V_UV= 100 VDC

V_OV= 450 VDC

CONTROL

C

S

-

PI-2523-062915

Figure 23. Active-off Remote ON/OFF with Line Sense.

13

Rev. C 06/15

www.power.com

TOP232-234

TOPSwitch-FX drain voltage, with adequate margin, under

worst case conditions. The extended maximum duty cycle

feature of TOPSwitch-FX (guaranteed minimum value of 75%

vs. 64% for TOPSwitch-II) allows the use of a smaller input

capacitor (C1). The extended maximum duty cycle and the

higher reﬂected voltage possible with the RCD clamp also

permit the use of a higher primary to secondary turns ratio for

T1 which reduces the peak reverse voltage experienced by the

secondary rectiﬁer D8. As a result, a 60 V Schottky rectiﬁer

can be used for up to 15 V outputs, which greatly improves

power supply efﬁciency. The cycle skipping feature of the

TOPSwitch-FX eliminates the need for any dummy loading for

regulation at no load and reduces the no load/standby

consumption of the power supply. Frequency jitter provides

improved margin for conducted EMI meeting the CISPR 22

(FCC B) speciﬁcation.

Application Examples

A High Efﬁciency, 30 W, Universal Input Power Supply

The circuit shown in Figure 24 takes advantage of several of

the TOPSwitch-FX features to reduce system cost and power

supply size and to improve efﬁciency. This design delivers 30 W

at 12 V, from an 85 to 265 VAC input, at an ambient of 50 ˚C,

in an open frame conﬁguration. A nominal efﬁciency of 80% at

full load is achieved using TOP234.

The current limit is externally set by resistors R1 and R2 to a

value just above the low line operating peak current of

approximately 70% of the default current limit. This allows use

of a smaller transformer core size and/or higher transformer

primary inductance for a given output power, reducing

TOPSwitch-FX power dissipation, while at the same time

avoiding transformer core saturation during startup and output

transient conditions. The resistor R1 provides a feed-forward

signal that reduces the current limit with increasing line

voltage, which, in turn, limits the maximum overload power at

high input line voltage. The feed-forward function in

A simple Zener sense circuit is used for low cost. The output

voltage is determined by the Zener diode (VR2) voltage and

the voltage drops across the optocoupler (U2) LED and

resistor R6. Resistor R8 provides bias current to Zener VR2 for

typical regulation of 5% at the 12 V output level, over line and

load and component variations.

combination with the built-in soft-start feature of TOPSwitch-

FX, allows the use of a low cost RCD clamp (R3, C3 and D1)

with a higher reﬂected voltage, by safely limiting the

CY1

2.2 nF

C14 R15

1 nF 150 Ω

L3

3.3 µH

12 V

@ 2.5 A

R3

68 kΩ

2W

C3

4.7 nF

1KV

C12

220 µF

35 V

D8

MBR1060

C10

560 µF

35 V

C11

560 µF

35 V

BR1

600 V

2A

RTN

D1

UF4005

R1

D2

1N4148

4.7 MΩ

1/2 W

R6

150 Ω

L1

20 mH

R8

150 Ω

T1

C6

100 nF

U2

C1

68 µF

400 V

LTV817A

CX1

TOPSwitch-FX

U1

D

S

M

100 nF

TOP234Y

250 VAC

CONTROL

C

R5

6.8 Ω

F1

3.15 A

R2

9.09 kΩ

F

VR2

1N5240C

10 V, 2%

J1

L

C5

47 µF

10 V

N

PI-2525-062515

Figure 24. 30 W Power Supply using External Current Limit.

14

Rev. C 06/15

www.power.com

TOP232-234

CONTROL pin instead of the SOURCE pin in video noise

sensitive applications to allow for heavier snubbing without

signiﬁcant impact on efﬁciency.

35 W Multiple Output Power Supply

Figure 25 shows a ﬁve output, 35 W, secondary regulated

power supply utilizing a TOP233 for multiple output applications

such as set-top box, VCR, DVD, etc. The circuit shown is

designed for a 230 VAC input but can be used over the

universal range at a derated output power of 25 W. Alternatively,

a doubler input stage can be used at 100 or 115 VAC for the

full power rating of 35 W. TOPSwitch-FX provides several

advantages in the above mentioned applications.

This design achieves 5% load regulation on 3.3 V and 5 V

outputs using dual sensed optocoupler feedback through

resistors R9, R10 and R11. Other output voltages are set by

the transformer turns ratio. Output voltage on the low power

-5 V output is shunt regulated by resistor R12 and Zener diode

VR2. Dummy load resistor R13 is required to maintain

regulation of the 30 V output under light load conditions.

Compensation of the TL431 (U3) is achieved with resistor R8

and capacitor C7. Primary side compensation and auto-

restart frequency are determined by resistor R5 and capacitor

C5. Second stage LC post-ﬁltering is used on the 3.3 V, 5 V

and 18 V high power outputs (L2, L3, L4 and C13, C15, C17)

for low ripple. Full load operating efﬁciency exceeds 75%

across the AC input range. Primary clamp components VR1

and D1 limit peak drain voltage to a safe value.

A single line sense resistor R1 (2 MΩ) implements an under-

voltage detect (at 100 V), overvoltage shutdown (at 450 V) and

line feed-forward with DC_MAXreduction features. Under-

voltage detect ensures that the outputs are glitch free on

power down. The over-voltage shutdown turns off the

TOPSwitch-FX MOSFET above 450 V on the DC input rail,

eliminating reﬂected voltage and leakage inductance spikes,

and hence, extending the surge withstand to the 700 VDC

rating of the MOSFET. This feature prevents ﬁeld failures in

countries where prolonged line voltage surges are common.

The frequency jittering in TOPSwitch-FX helps reduce EMI,

maintaining emissions below CISPR 22 (FCC B) levels through

proper choice of Y1 capacitor (CY1) and input ﬁltering elements

(CX1, L1). To minimize coupling of common mode transients to

the TOP233, Y1 capacitor is tied to the positive input DC rail.

Lightning strike immunity to 3 kV is attained with the addition

of a 275 V MOV (RV1).

This design also takes advantage of soft-start and higher

operating frequency to reduce transformer size. A snubber

circuit (R4, C4) is used to slowdown dv/dt of the switching

waveform minimizing radiated video noise that could interfere

with TV reception. The half frequency option of the TOPSwitch-FX

can be used by connecting the FREQUENCY pin to the

30 V

@ 100 mA

C11

D8

MUR120

C10

1 µF

L2

3.3 µH

100 µF

18 V

@ 550 mA

50 V

C12

220 µF

25 V

C13

100 µF

25 V

D9

CY1

2.2 nF

R13

UF5402

L3

3.3 µH

24 kΩ

5 V

@ 2.5 A

D10

MBR1045

C14

C15

100 µF

10 V

1000 µF

L4

3.3 V

@ 3 A

25 V

3.3 µH

VR1

P6KE200

D11

BYW29-

100

C16

C17

100 µF

10 V

1000 µF

25 V

D1

UF4007

RTN

BR1

400 V

C18

C19

330 µF

VR2

1N5231

100 µF

D12

1N5819

R12

5 Ω

-5 V

@ 100 mA

10 V

C1

33 µF

400 V

L1

20 mH

D2

1N4148

R6

51 Ω

R1

2 MΩ

1/2 W

R10

15.0 kΩ

T1

U2

LTV817

R7

CX1

0.1 µF

510 Ω

C6

100 nF

R9

9.53 kΩ

TOPSwitch-FX

U1

250 VAC

D

S

M

C4

TOP233Y

47 pF

CONTROL

C7

R8

F1

C

10 Ω 0.1 µF

3.15 A

R4

2 kΩ

R5

6.8 Ω

F

J1

L

U3

TL431CLP

C5

47 µF

C8

22 µF

RV1

275 V

R11

10.0 kΩ

N

PI-2536-062515

Figure 25. 35 W Set-Top Box Power Supply.

1ꢀ

Rev. C 06/15

www.power.com

TOP232-234

17 W PC Standby Power Supply

This is achieved by turning the power supply off when the

input voltage goes below a level needed to maintain output

regulation and keeping it off until the input voltage goes above

the under-voltage threshold (V_UV), when the AC is turned on

again. The under voltage threshold is set at 200 VDC, slightly

below the required lowest operating DC input voltage, for

start-up at 170 VAC. This feature saves several components

needed to implement the glitch free turn off with discrete or

TOPSwitch-II based designs.

Figure 26 shows a 17 W PC standby application with 3.3 V

and 5 V secondary outputs and a 15 V primary output. The

supply uses the TOP232 operating from 230 VAC or 100/

115 VAC with doubler input. This design takes advantage of

the soft-start, line under-voltage detect, tighter current limit

variation and higher switching frequency features of

TOPSwitch-FX. For example, the higher switching frequency

with tighter current limit variation allows use of an EE19

transformer core. Furthermore, the spacing between high-

voltage DRAIN pin and low voltage pins of the TOPSwitch-FX

packages provides large creepage distance which is a

signiﬁcant advantage in high pollution environments such as

fan cooled PC power supplies.

The bias winding is rectiﬁed and ﬁltered by D2 and C6 to

create a bias voltage for the TOP232 and to provide a 15 V

primary bias output voltage for the main power supply primary

control circuitry. Both 3.3 V and 5 V output voltages are

sensed by R9, R10 and R11 using a TL431 (U3) circuit shown.

Resistor R6 limits current through optocoupler U2 and sets

overall AC control loop gain. Resistor R7 assures that there is

sufﬁcient bias current for the TL431 when the optocoupler is at

a minimum current. Capacitor C8 provides a soft-ﬁnish

function to eliminate turn-on overshoot. The no load regulation

(cycle-skipping) of TOPSwitch-FX permits the circuit to meet

the low standby power requirement of the Blue Angel

speciﬁcation for PCs.

Capacitor C1 provides high frequency decoupling of the

high-voltage DC supply, and is necessary only if there is a long

trace length from the source of the DC supply to the inputs of

this standby circuit. The line sense resistor R1 senses the DC

input voltage for line undervoltage. When AC is turned off, the

under-voltage detect feature of the TOPSwitch-FX prevents

auto-restart glitches at the output caused by the slow

discharge of large storage capacitance in the main converter.

CY1

1 nF

L1

3.3 µH

5 V

@ 2 A

C10

C11

100 µF

10 V

D3

L2

3.3 µH

1000 µF

3.3 V

+

SB540

10 V

@ 2 A

VR1

BZY97C-

200

C12

1000 µF

10 V

C13

100 µF

10 V

D4

SB540

RTN

200 - 375

VDC

R1

3.9 MΩ

15 V

D1

UF4005

@ 30 mA

D2

BAV21

R6

301 Ω

(Primary

Referenced)

C1

R9

16.2 kΩ

R7

510 Ω

T1

0.01 µF

1 kV

(optional)

C6

35 V

U2

SFH615-2

TOPSwitch-FX

U1

TOP232Y

C

D

S

M

R10

12.1 kΩ

CONTROL

C7

0.1 µF

R5

6.8 Ω

F

C8

U3

TL431CLP

10 µF

R11

10 kΩ

C5

47 µF

35 V

–

PI-2537-062515

Figure 26. 17 W PC Standby Supply.

16

Rev. C 06/15

www.power.com

TOP232-234

Processor Controlled Supply Turn On/Off

In the case of products with a disk drive, the shutdown

procedure may include saving data or settings to the disk.

After the shutdown procedure is complete, when it is safe to

turn off the power supply, the microprocessor releases the

M pin by turning the optocoupler U4 off. If the manual switch

and the optocouplers U3 and U4 are not located close to the

M pin, a capacitor C_Mmay be needed to prevent noise

coupling to the pin when it is open.

A low cost momentary contact switch can be used to turn the

TOPSwitch-FX power on and off under microprocessor control

that may be required in some applications such as printers.

The low power remote off feature allows an elegant implemen-

tation of this function with very few external components as

shown in Figure 27. Whenever the push button momentary

contact switch P1 is closed by the user, the optocoupler U3 is

activated to inform the microprocessor of this action. Initially,

when the power supply is off (M pin is ﬂoating), closing of P1

turns the power supply on by shorting the M pin of the

TOPSwitch-FX to SOURCE through a diode (remote on). When

the secondary output voltage VCC is established, the micro-

processor comes alive and recognizes that the switch P1 is

closed through the switch status input that is driven by the

optocoupler U3 output. The microprocessor then sends a

power supply control signal to hold the power supply in the

on-state through the optocoupler U4. If the user presses the

switch P1 again to command a turn off, the microprocessor

detects this through the optocoupler U3 and initiates a

shutdown procedure that is product speciﬁc. For example, in

the case of the inkjet printer, the shutdown procedure may

include safely parking the print heads in the storage position.

The power supply could also be turned on remotely through a

local area network or a parallel or serial port by driving the

optocoupler U4 input LED with a logic signal. Sometimes it is

easier to send a train of logic pulses through a cable (due to

AC coupling of cable, for example) instead of a DC logic level

as a wake-up signal. In this case, a simple RC ﬁlter can be

used to generate a DC level to drive U4 (not shown in Figure

27). This remote on feature can be used to wake-up

peripherals such as printers, scanners, external modems, disk

drives, etc., as needed from a computer. Peripherals are

usually designed to turn off automatically if they are not being

used for a period of time, to save power.

V_CC

(+5 V)

+

External

Wake-up

Signal

High-Voltage

DC Input

Power

Supply

ON/OFF

Control

MICRO-

PROCESSOR/

CONTROLLER

100 kΩ

27 kΩ

U2

1N4148

LOGIC LOGIC

INPUT OUTPUT

1N4148

6.8 kΩ

TOPSwitch-FX

C

D

S

M

U3

U4

CONTROL

6.8 kΩ

C_M

1 nF

47 µF

F

U4

LTV817A

U1

U3

LTV817A

P1

P1 Switch

Status

RETURN

–

PI-2561-062615

Figure 27. Remote ON/OFF using Microcontroller.

17

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TOP232-234

In addition to using a minimum number of components,

TOPSwitch-FX provides many technical advantages in this

type of application:

shutdown sequence when it detects the ﬁrst closure of the

switch, and subsequent bouncing of the switch has no

effect. If necessary, the microprocessor could implement

the switch debouncing in software during turn-off, or a ﬁlter

capacitor can be used at the switch status input.

4. No external current limiting circuitry is needed for the

operation of the U4 optocoupler output due to internal

limiting of M pin current.

5. No high-voltage resistors to the input DC voltage rail are

required to power the external circuitry in the primary. Even

the LED current for U3 can be derived from the CONTROL

pin. This not only saves components and simpliﬁes layout,

but also eliminates the power loss associated with the

high-voltage resistors in both on and off states.

1. Extremely low power consumption in the off mode: 80 mW

typical at 110 VAC and 160 mW typical at 230 VAC. This is

because in the remote/off mode the TOPSwitch-FX

consumes very little power, and the external circuitry does

not consume any current (M pin is open) from the high-

voltage DC input.

2. A very low cost, low voltage/current, momentary contact

switch can be used.

3. No debouncing circuitry for the momentary switch is

required. During turn-on, the start-up time of the power

supply (typically 10 to 20 ms) plus the microprocessor

initiation time act as a debouncing ﬁlter, allowing a turn-on

only if the switch is depressed ﬁrmly for at least the above

delay time. During turn-off, the microprocessor initiates the

6. Robust design: There is no on/off latch that can be

accidentally triggered by transients. Instead, the power

supply is held in the on-state through the secondary side

microprocessor.

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TOP232-234

Key Application Considerations

TOPSwitch-FX vs. TOPSwitch-ll

Table 3 compares the features and performance differences

between TOPSwitch-FX and TOPSwitch-II. Many of the new

features eliminate the need for costly discrete component.

Other features increase the robustness of design allowing

cost savings in the transformer and other power components.

Function

TOPSwitch-II

TOPSwitch-FX

Figures Advantages

Soft-Start

N/A*

10 ms

• Limits peak current and voltage

component stresses during start-up

• Eliminates external components

used for soft-start in most applications

• Minimizes output overshoot

External Current Limit

N/A*

67%

Programmable

100% to 40% of

default current

limit

8, 17,

18, 21,

22

• Smaller transformer

• Higher efﬁciency

• Allows tighter power limit

during output overload conditions

DC_MAX

78%

4

• Smaller input cap (wider dynamic range)

• Higher power capability (when used

with RCD clamp for large V_OR)

• Allows use of Schottky secondary

rectiﬁer diode for up to 15 V output

for high efﬁciency

Line Feed-forward with

DC_MAXReduction

N/A*

78% to 38%

4, 8, 14, • Rejects line ripple

23

• Increases transient and surge voltage

withstand capability

Line OV Shutdown

Line UV Detection

Switching Frequency

N/A*

Single resistor

programmable

8, 14,

16, 23

• Increases voltage withstand capability

against line surge

N/A*

Single resistor

programmable

5, 8, 14, • Prevents auto-restart glitches during

15, 23

power-down

100 kHz 10%

132 kHz 7%

10

• Smaller transformer

• Fundamental below 150 kHz for

conducted EMI

Switching Frequency

Option (TO-220 only)

N/A*

66 kHz 7%

11, 12

• Lower losses when using RC and RCD

snubber for noise reduction in video

applications

• Allows for higher efﬁciency in standby

mode

• Lower EMI (second harmonic below

150 kHz)

Frequency Jitter

Cycle Skipping

N/A*

4 kHz@132 kHz

2 kHz@66 kHz

6, 28

4

• Reduces conducted EMI

At DC_MIN(1.5%)

• Zero load regulation without dummy

load

• Low power consumption at no load

*Not available

Table 3. Comparison Between TOPSwitch-II and TOPSwitch-FX. (continued on next page)

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TOP232-234

Function

TOPSwitch-II

TOPSwitch-FX

Figures Advantages

Remote ON/OFF

N/A*

Single transistor

or optocoupler

interface or manual

switch

8, 19,

20, 21,

• Fast on/off (cycle by cycle)

• Active-on or active-off control

22, 23, • Low consumption in remote off state

27

• Active-on control for fail-safe

• Eliminates expensive in-line on/off

switch

• Allows processor controlled turn on/off

• Permits shutdown/wake-up of

peripherals via LAN or parallel port

Synchronization

N/A*

Single transistor

or optocoupler

interface

• Synchronization to external lower

frequency signal

• Starts new switching cycle on demand

Thermal Shutdown

Current Limit Tolerance

Latched

10% (@25 °C)

Hysteretic (with

70 °C hysteresis)

• Automatic recovery from thermal fault

• Large hysteresis prevents circuit

board overheating

7% (@25 °C)

• 10% higher power capability due to

tighter tolerance

-8% (0 °C to100 °C) -4% (0 °C to 100 °C)

DRAIN

DIP

0.037” / 0.94 mm

0.137” / 3.48 mm

0.068” / 1.73 mm

• Greater immunity to arcing as a

result of build-up of dust, debris and

other contaminants

Creepage at

Package

SMD

TO-220 0.046” / 1.17 mm

0.045” / 1.14 mm

DRAIN Creepage at

PCB for TO-220

0.113” / 2.87 mm

(preformed leads)

• Preformed leads accommodate

large creepage for PCB layout

• Easier to meet Safety (UL/VDE)

*Not available

Table 3 (cont). Comparison Between TOPSwitch-II and TOPSwitch-FX.

Primary Clamp and Output Reﬂected Voltage V_OR

A primary clamp is necessary to limit the peak TOPSwitch-FX

drain to source voltage. A Zener clamp (see Figure 26, VR1)

requires few parts and takes up little board space. For good

efﬁciency, the clamp Zener should be selected to be at least

1.5 times the output reﬂected voltage V_ORas this keeps the

leakage spike conduction time short. When using a Zener

clamp in a universal input application, a V_ORof less than 135 V

is recommended to allow for the absolute tolerances and

temperature variations of the Zener. This will ensure efﬁcient

operation of the clamp circuit and will also keep the maximum

drain voltage below the rated breakdown voltage of the

TOPSwitch-FX MOSFET.

TOPSwitch-FX Design Considerations

TOPSwitch-FX Selection

Selecting the optimum TOPSwitch-FX depends upon required

maximum output power, efﬁciency, heat sinking constraints

and cost goals. With the option to externally reduce current

limit, a larger TOPSwitch-FX may be used for lower power

applications where higher efﬁciency is needed or minimal heat

sinking is available.

Input Capacitor

The input capacitor must be chosen to provide the minimum

DC voltage required for the TOPSwitch-FX converter to

maintain regulation at the lowest speciﬁed input voltage and

maximum output power. Since TOPSwitch-FX has a higher

DC_MAXthan TOPSwitch-II, it is possible to use a smaller input

capacitor. For TOPSwitch-FX, a capacitance of 2 µF per watt

is usually sufﬁcient for universal input with an appropriately

designed transformer.

A high V_ORis required to take full advantage of the wider DC_MAX

of TOPSwitch-FX. An RCD clamp provides tighter clamp

voltage tolerance than a Zener clamp and allows a V_ORas high

as 165 V. The V_ORcan be further increased in continuous

mode designs up to 185 V by reducing the external current

limit as a function of input line voltage (see Figure 18). The

RCD clamp is more cost effective than the Zener clamp but

requires more careful design (see quick design checklist).

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TOP232-234

Output Diode

The output diode is selected for peak inverse voltage, output

current, and thermal conditions in the application (including

heat sinking, air circulation, etc.). The higher DC_MAXof

TOPSwitch-FX along with an appropriate transformer turns

ratio can allow the use of a 60 V Schoktty diode for higher

efﬁciency on output voltages as high as 15 V (See Figure 24.

A 12 V, 30 W design using a 60 V Schottky for the output

diode).

Average

Soft-Start

Quasi-Peak

Generally a power supply experiences maximum stress at

start-up before the feedback loop achieves regulation. For a

period of 10 ms the on-chip soft-start linearly increases the

duty cycle from zero to the default DC_MAXat turn on, which

causes the primary current and output voltage to rise in an

orderly manner allowing time for the feedback loop to take

control of the duty cycle. This reduces the stress on the

TOPSwitch-FX MOSFET, clamp circuit and output diode(s),

and helps prevent transformer saturation during start-up. Also,

soft-start limits the amount of output voltage overshoot, and in

many applications eliminates the need for a soft-ﬁnish

capacitor.

Switching Harmonic

(a)

80

70

60

50

40

30

TOPSwitch-II (no jitter)

EMI

The frequency jitter feature modulates the switching frequency

over a narrow band as a means to reduce conducted EMI

peaks associated with the harmonics of the fundamental

switching frequency. This is particularly beneﬁcial for average

detection mode. As can be seen in Figure 28, the beneﬁts of

jitter increase with the order of the switching harmonic due to

an increase in frequency deviation.

20

-10

0

VFG243B (QP)

VF646B (AV)

-10

-20

The FREQUENCY pin of TOPSwitch-FX offers a switching

frequency option of 132 kHz or 66 kHz. In applications that

require heavy snubbers on the drain node for reducing high

frequency radiated noise (for example, video noise sensitive

applications such as VCR, DVD, monitor, TV, etc.), operating at

66 kHz will reduce snubber loss resulting in better efﬁciency.

Also, in applications where transformer size is not a concern,

use of the 66 kHz option will provide lower EMI and higher

efﬁciency. Note that the second harmonic of 66 kHz is still

below 150 kHz, above which the conducted EMI speciﬁcations

get much tighter.

0.15

1

10

30

Frequency (MHz)

(b)

80

70

60

TOPSwitch-FX (with jitter)

50

40

30

20

-10

0

For 10 W or below, it is possible to use a simple inductor in

place of a more costly AC input common mode choke to meet

worldwide conducted EMI limits.

Transformer Design

It is recommended that the transformer be designed for

maximum operating ﬂux density of 3000 gauss and a peak

ﬂux density of 4200 gauss at maximum current limit. The

turns ratio should be chosen for a reﬂected voltage (V_OR) no

greater than 135 V when

VFG243B (QP)

VF646B (AV)

-10

-20

0.15

1

10

30

Frequency (MHz)

(c)

Figure 28. (a) Conducted Noise Improvement for Low Frequency

Harmonics due to Jitter, (b) TOPSwitch-II Full Range EMI Scan

(100 kHz, no Jitter), (c) TOPSwitch-FX Full Range EMI Scan

(132 kHz, with Jitter) with Identical Circuitry and Conditions.

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TOP232-234

Maximize hatched copper

areas (

heat sinking

) for optimum

Safety Spacing

Y1-

Capacitor

+

Output Filter Capacitor

J1

Input Filter Capacitor

HV

–

T

r

PRI

SEC

a

n

s

f

S

D

o

r

m

e

r

BIAS

TOPSwitch-FX

TOP VIEW

M

S

C

Opto-

coupler

R1

DC

Out

+

–

PI-2543-062615

Figure 29. Layout Considerations for TOPSwitch-FX using DIP or SMD (Using Line Sensing for Under-Voltage and Overvoltage).

Maximize hatched copper

areas (

) for optimum

Safety Spacing

heat sinking

Y1-

Capacitor

+

Output Filter Capacitor

J1

Input Filter Capacitor

HV

–

T

r

a

n

s

f

o

r

m

e

r

PRI

SEC

D

C

F

BIAS

S

R1

M

Heat Sink

R2

TOPSwitch-FX

TOP VIEW

Opto-

coupler

DC

Out

–

+

PI-2544-062615

Figure 30. Layout Considerations for TOPSwitch-FX using TO-220 Package (Using Current Limit Reduction with Line Voltage).

22

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TOP232-234

using a Zener clamp, 165 V when using an RCD clamp and

185 V when using RCD clamp with current limit feed-forward.

When using P (DIP-8) or G (SMD-8) packages, a copper area

underneath the package connected to the SOURCE pins will

act as an effective heat sink.

For designs where operating current is signiﬁcantly lower than

the default current limit, it is recommended to use an externally

set current limit close to the operating peak current to reduce

peak ﬂux density and peak power (see Figure 17). In most

applications, the tighter current limit tolerance, higher switching

frequency and soft-start features of TOPSwitch-FX contribute

to a smaller transformer when compared to TOPSwitch-II.

In addition, sufﬁcient copper area should be provided at the

anode and cathode leads of the output diode(s) for heat

sinking.

Quick Design Checklist

As with any power supply design, all TOPSwitch-FX designs

should be veriﬁed on the bench to make sure that components

speciﬁcations are not exceeded under worst case conditions.

The following minimum set of tests is strongly recommended:

1. Maximum drain voltage – Verify that peak V_DSdoes not

exceed 675 V at highest input voltage and maximum

overload output power. Maximum overload output power

occurs when the ouput is overloaded to a level just before

the power supply goes into auto-restart (loss of regulation).

2. Maximum drain current – At maximum ambient

temperature, maximum input voltage and maximum output

load, verify drain current waveforms at start-up for any

signs of transformer saturation and excessive leading edge

current spikes. TOPSwitch-FX has a leading edge blanking

time of 200 ns to prevent premature termination of the

on-cycle. Verify that the leading edge current spike is

below the allowed current limit envelope (see Figure 33) for

the drain current waveform at the end of the 200 ns

blanking period.

3. Thermal check – At maximum output power, minimum

input voltage and maximum ambient temperature, verify

that temperature speciﬁcations are not exceeded for

TOPSwitch-FX, transformer, output diodes and output

capacitors. Enough thermal margin should be allowed for

the part-to-part variation of the R_DS(ON)of TOPSwitch-FX as

speciﬁed in the data sheet. The margin required can either

be calculated from the tolerances or it can be accounted

for by connecting an external resistance in series with the

DRAIN pin and attached to the same heat sink, having a

resistance value that is equal to the difference between the

measured R_DS(ON)of the device under test and the worst

case maximum speciﬁcation.

Standby Consumption

Cycle skipping can signiﬁcantly reduce power loss at zero

load, especially when a Zener clamp is used. For very low

secondary power consumption use a TL431 regulator for

feedback control. Alternately, switching losses can be

signiﬁcantly reduced by switching from 132 kHz in normal

operation to 66 kHz under light load conditions.

TOPSwitch-FX Layout Considerations

Primary Side Connections

Use a single point (Kelvin) connection at the negative terminal

of the input ﬁlter capacitor for TOPSwitch-FX SOURCE pin and

bias winding return. This improves surge capabilities by

returning surge currents from the bias winding directly to the

input ﬁlter capacitor.

The CONTROL pin bypass capacitor should be located as

close as possible to the SOURCE and CONTROL pins and its

SOURCE connection trace should not be shared by the main

MOSFET switching currents.

All SOURCE pin referenced components connected to the

MULTI-FUNCTION pin should also be located close to

SOURCE and MULTI-FUNCTION pins with dedicated

SOURCE pin connection. The MULTI-FUNCTION pin’s trace

should be kept as short as possible and away from the DRAIN

trace to prevent noise coupling. Line sense resistor (R1 in

Figures 29 and 30) should be located close to the MULTI-

FUNCTION pin to minimize the trace length on the MULTI-

FUNCTION pin side.

Design Tools

In addition to the 47 µF CONTROL pin capacitor, a high

frequency bypass capacitor in parallel may be used for better

noise immunity. The feedback optocoupler output should also

be located close to the CONTROL and SOURCE pins of

TOPSwitch-FX.

1. Technical literature: Data Sheet, Application Notes, Design

Ideas, etc.

2. ransformer design spreadsheet.

3. Engineering prototype boards.

Y-Capacitor

Up to date information on design tools can be found at Power

Integrations Web site: www.power.com

The Y-capacitor should be connected close to the secondary

output return pin(s) and the primary DC input pin of the

transformer (see Figures 29 and 30).

Heat Sinking

The tab of the Y package (TO-220) is internally electrically

tied to the SOURCE pin. To avoid circulating currents, a heat

sink attached to the tab should not be electrically tied to any

nodes on the PC board.

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TOP232-234

ABSOLUTE MAXIMUM RATINGS^(1,4)

Lead Temperature⁽³⁾...................................................260 °C

Notes:

1. All voltages referenced to SOURCE, T_A= 25 °C.

2. Normally limited by internal circuitry.

DRAIN Pin Voltage ........................................... -0.3 to 700 V

DRAIN Pin Peak Current: TOP232 ................................0.8 A

TOP233 ................................1.6 A

TOP234 ................................2.4 A

CONTROL Pin Voltage......................................... -0.3 to 9 V

CONTROL Pin Current..............................................100 mA

MULTI-FUNCTION Pin Voltage............................. -0.3 to 9 V

FREQUENCY Pin Voltage..................................... -0.3 to 9 V

Operating Junction Temperature⁽²⁾.................. -40 to 150 °C

3. 1/16” from case for 5 seconds.

4. The Absolute Maximum Ratings speciﬁed may be applied,

one at a time without causing permanent damage to the

product. Exposure to Absolute Maximum Ratings for ex-

tended periods of time may affect product reliability.

THERMAL RESISTANCE

Thermal Resistance: Y Package

Notes:

(θ_JA)⁽¹⁾...................................... 70 °C/W 1. Free standing with no heat sink.

(θ_JC)⁽²⁾........................................ 2 °C/W 2. Measured at the back surface of tab.

P/G Package:

3. Soldered to 0.36 sq. inch (232 mm²), 2oz. (610 gm/m²) copper clad.

(θ_JA) .....................45 °C/W⁽³⁾; 35 °C/W⁽⁴⁾4. Soldered to 1 sq. inch (645 mm²), 2oz. (610 gm/m²) copper clad.

(θ_JC)⁽⁵⁾...................................... 11 °C/W 5. Measured on the SOURCE pin close to plastic interface.

Conditions

(Unless Otherwise Speciﬁed)

Parameter

Symbol

Min

Typ Max

Units

See Figure 34

SOURCE = 0 V; T_J= -40 to 125 °C

CONTROL FUNCTIONS

FREQUENCY Pin

Connected to SOURCE

124

132

66

140

Switching

I_C= 4 mA;

T_J= 25 °C

kHz

f_OSC

Frequency

FREQUENCY Pin

Connected to CONTROL

(average)

61.5

70.5

4

2

132 kHz Operation

66 kHz Operation

Frequency Jitter

Deviation

∆f

Frequency Jitter

f_M

Hz

%

250

Modulation Rate

I_M≤ I_M(DC)

75.0

35.0

78.0

47.0

82.0

57.0

Maximum Duty

DC_MAX

I_C= I_CD1

Cycle

I_M= 190 µA

Minimum Duty

DC_MIN

%

Cycle (Prior to

0.8

1.5

2.7

Cycle Skipping)

T_J= 25 °C; DC_MINtoDC_MAX

t_SOFT

ms

Soft Start Time

10

14

PWM

Gain

%/mA

-27

-22

-17

I_C= 4 mA; T_J= 25 °C

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TOP232-234

Conditions

(Unless Otherwise Speciﬁed)

See Figure 34

Parameter

Symbol

Min

Typ Max

Units

SOURCE = 0 V; T_J= -40 to 125 °C

CONTROL FUNCTIONS (cont.)

PWM Gain

- 0.01

1.9

%/mA/°C

See Note A

See Figure 4

Temperature Drift

External Bias

Current

l_B

mA

1.2

10

2.8

7.5

22

CONTROL

Current at Start of

Cycle Skipping

T_J= 25 °C

mA

Ω

5.9

Dynamic

Z_C

I_C= 4 mA; T_J= 25 °C

15

Impedance

See Figure 32

Dynamic

0.18

%/°C

Impedance

Temperature Drift

Control Pin

Internal Filter Pole

kHz

7

SHUTDOWN/AUTO-RESTART

V_C= 0 V

V_C= 5 V

-5.0

-3.0

-3.8

-1.9

-2.6

-0.8

Control Pin

Charging Current

l_{C (CH)}

T_J= 25 °C

mA

Charging Current

Temperature Drift

See Note A

0.5

5.8

%/°C

V

Auto-restart Upper

Threshold Voltage

v_C(AR)

Auto-restart Lower

Threshold Voltage

4.5

0.8

2

4.8

1.0

4

5.1

8

V

Auto-restart

Hysteresis Voltage

V

Auto-restart Duty

Cycle

%

Auto-restart

Frequency

1.0

Hz

2ꢀ

Rev. C 06/15

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TOP232-234

Conditions

(Unless Otherwise Speciﬁed)

See Figure 34

Parameter

Symbol

Min

Typ Max

Units

SOURCE = 0 V; T_J= -40 to 125 °C

MULTI-FUNCTION INPUT

Line Undervoltage

l_UV

µA

T_J= 25 °C

44

50

225

10

54

Threshold Current

µA

Line Overvoltage or

Threshold

210

240

Remote ON/OFF

Threshold Current

and Hysteresis

I_OV

T_J= 25 °C

Hysteresis

Remote ON/OFF

Negative Threshold

Current and

Threshold

µA

-43

-35

-7

-27

I_{REM (N)}

T_J= 25 °C

Hysteresis

V_M= V_C

300

400

520

MULTI-FUNCTION

Pin Short Circuit

Current

I_{M (SC)}

Normal Mode

µA

-300

-240

-180

V_M= 0 V

Auto-restart Mode

-110

2.00

2.50

1.25

-90

-70

l_M= 50 µA

l_M= 225 µA

l_M= -50 µA

l_M= -150 µA

2.60

2.90

1.32

3.00

3.30

1.39

MULTI-FUNCTION

Pin Voltage

V

V_M

1.18

1.24

1.30

Maximum Duty

Cycle Reduction

Onset Threshold

Current

75

90

110

µA

%/µA

mA

I_{M (DC)}

T_J= 25 °C

Maximum Duty

Cycle Reduction

Slope

I_M> I_{M (DC)}

0.30

0.6

MULTI-FUNCTION

Pin Floating

MULTI-FUNCTION

1.1

1.8

Remote-OFF

DRAIN Supply

Current

V_DRAIN= 150 V

Pin Shorted to

CONTROL

1.0

From Remote On to Drain Turn-On

See Note B

µs

1.5

2.5

4.0

Remote-ON Delay

T_RON

Minimum Time Before Drain

Turn-On to Disable Cycle

See Note B

Remote-OFF

Setup Time

T_ROFF

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TOP232-234

Conditions

(Unless Otherwise Speciﬁed)

See Figure 34

Parameter

Symbol

Min Typ

Max

Units

SOURCE = 0 V; T_J= -40 to 125 °C

FREQUENCY INPUT

FREQUENCY Pin

Threshold Voltage

V_F

I_F

See Note B

V_F= V_C

1.0

10

2.9

22

V_C-1.0

40

V

FREQUENCY Pin

Input Current

µA

CIRCUIT PROTECTION

TOP232

T_J= 25 °C

Internal; di/dt = 100mA/µs

0.465 0.500 0.535

0.930 1.000 1.070

1.395 1.500 1.605

See Note C

Internal; di/dt = 200mA/µs

TOP233

T_J= 25 °C

Self Protection

Current Limit

I_LIMIT

A

See Note C

Internal; di/dt = 300mA/µs

TOP234

T_J= 25 °C

See Note C

0.75 x

I_LIMIT(MIN)

≤ 85 VAC

(Rectiﬁed Line Input)

See Figure 33

T_J= 25 °C

I_INIT

Initial Current Limit

0.6 x

I_LIMIT(MIN)

265 VAC

(Rectiﬁed Line Input)

Leading Edge

Blanking Time

t_LEB

t_ILD

ns

I_C= 4 mA

200

100

Current Limit Delay

I_C= 4 mA

Thermal Shutdown

Temperature

125

2.0

135

150

4.3

°C

V

Thermal Shutdown

Hysteresis

70

Power-up Reset

Threshold Voltage

3.3

V_C(RESET)

Figure 34, S1 open

OUTPUT

T_J= 25 °C

T_J= 100 °C

T_J= 25 °C

T_J= 100 °C

T_J= 25 °C

T_J= 100 °C

TOP232

I_D= 50 mA

15.6

25.7

7.8

18.0

30.0

9.0

ON-State

Resistance

TOP233

I_D= 100 mA

R_DS(ON)

Ω

12.9

5.2

15.0

6.0

TOP234

I_D= 150 mA

8.6

10.0

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TOP232-234

Conditions

(Unless Otherwise Speciﬁed)

See Figure 34

Parameter

Symbol

Min

Typ

Max

Units

SOURCE = 0 V; T_J= -40 to 125 °C

OUTPUT (cont.)

V_M= Floating; I_C= 4mA

V_DS= 560 V; T_J= 125 °C

Off-State

Current

I_DSS

150

µA

V

V_M= Floating; I_C= 4mA

I_D= 100 µA; T_J= 25 °C

Breakdown

Voltage

700

BV_DSS

t_R

100

50

ns

Rise Time

Fall Time

Measured in a Typical

Flyback Converter Application

t_F

ns

SUPPLY VOLTAGE CHARACTERISTICS

DRAIN Supply

Voltage

36

V

See Note D

Shunt Regulator

Voltage

V_C(SHUNT)

5.60

5.85

50

6.10

V

I_C= 4 mA

Shunt Regulator

Temperature Drift

ppm/°C

Output

MOSFET Enabled

V_M= 0 V

l_CD1

1.0

0.3

1.5

0.6

2.0

1.0

Control Supply/

Discharge Current

mA

Output

MOSFET Disabled

V_M= 0 V

l_CD2

NOTES:

A. For speciﬁcations with negative values, a negative temperature coefﬁcient corresponds to an increase in magnitude

with increasing temperature, and a positive temperature coefﬁcient corresponds to a decrease in magnitude with

increasing temperature.

B. Guaranteed by characterization. Not tested in production.

C. For externally adjusted current limit values, please refer to the graph (Current Limit vs. External Current Limit Resis-

tance) in the Typical Performance Characteristics section.

D. It is possible to start up and operate TOPSwitch-FX at DRAIN voltages well below 36 V. However, the CONTROL pin

charging current is reduced, which affects start-up time, auto-restart frequency, and auto-restart duty cycle. Refer to

the characteristic graph on CONTROL pin charge current (I_C) vs. DRAIN voltage for low voltage operation characteristics.

28

Rev. C 06/15

www.power.com

TOP232-234

t

2

t

1

HV

90%

t

DRAIN

VOLTAGE

1

2

D =

10%

0 V

PI-2039-033001

Figure 31. Duty Cycle Measurement.

t

(Blanking Time)

LEB

1.3

1.2

1.1

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

120

100

80

60

40

20

0

I_INIT(MIN)@ 85 VAC

I_INIT(MIN)@ 265 VAC

I_LIMIT(MAX)@ 25 ˚C

1

Dynamic

I_LIMIT(MIN)@ 25 ˚C

=

Impedance Slope

0

1

2

3

4

5

6

7

8

0

2

4

6

8

10

CONTROL Pin Voltage (V)

Time (µs)

Figure 33. Drain Current Operating Envelope.

Figure 32. CONTROL Pin I-V Characteristic.

S1

470 Ω

5 W

100 kΩ

S3

5-50 V

40 V

0-60 kΩ

M

D

S

CONTROL

470 Ω

C

TOPSwitch-FX

S2

F

S4

0-15 V

47 µF

0.1 µF

NOTES: 1. This test circuit is not applicable for current limit or output characteristic measurements.

2. For P and G packages, short all SOURCE pins together.

PI-2538-062615

Figure 34. TOPSwitch-FX General Test Circuit.

29

Rev. C 06/15

www.power.com

TOP232-234

BENCH TEST PRECAUTIONS FOR EVALUATION OF ELECTRICAL CHARACTERISTICS

while in this auto-restart mode, there is only a 12.5% chance

that the CONTROL pin oscillation will be in the correct state

(drain active state) so that the continuous drain voltage

waveform may be observed. It is recommended that the V_C

power supply be turned on ﬁrst and the DRAIN pin power

supply second if continuous drain voltage waveforms are to be

observed. The 12.5% chance of being in the correct state is

due to the divide-by-8 counter. Temporarily shorting the

CONTROL pin to the SOURCE pin will reset TOPSwitch-FX,

which then will come up in the correct state.

The following precautions should be followed when testing

TOPSwitch-FX by itself outside of a power supply. The

schematic shown in Figure 34 is suggested for laboratory

testing of TOPSwitch-FX.

When the DRAIN pin supply is turned on, the part will be in the

auto-restart mode. The CONTROL pin voltage will be

oscillating at a low frequency between 4.8 and 5.8 V and the

drain is turned on every eighth cycle of the CONTROL pin

oscillation. If the CONTROL pin power supply is turned on

Typical Performance Characteristics

CURRENT LIMIT vs. MULTI-FUNCTION

PIN CURRENT

PI-2540-033001

200

180

160

140

120

100

1.0

.9

.8

.7

.6

Scaling Factors:

.5

.4

TOP234 1.50

TOP233 1.00

TOP232 0.50

80

60

.3

-250

-200

-150

-100

-50

0

I_M(µA)

CURRENT LIMIT vs. EXTERNAL

CURRENT LIMIT RESISTANCE

PI-2539-033001

1.1

1.0

200

Scaling Factors:

TOP234 1.50

TOP233 1.00

TOP232 0.50

.9

.8

.7

.6

180

160

140

120

Maximum

Minimum

Typical

.5

.4

.3

100

80

Maximum and minimum levels

are based on characterization.

60

30K

0

5K

10K

15K

20K

25K

External Current Limit Resistor R_IL(Ω)

30

Rev. C 06/15

www.power.com

TOP232-234

Typical Performance Characteristics (cont.)

BREAKDOWN vs. TEMPERATURE

FREQUENCY vs. TEMPERATURE

1.2

1.1

1.0

0.8

0.6

0.4

1.0

0.9

0.2

0

-50 -25

0

25 50 75 100 125 150

-50 -25

0

25 50 75 100 125 150

Junction Temperature (°C)

OVER-VOLTAGE THRESHOLD

vs. TEMPERATURE

UNDER-VOLTAGE THRESHOLD

vs. TEMPERATURE

Junction Temperature (°C)

OVER-VOLTAGE THRESHOLD

vs. TEMPERATURE

UNDER-VOLTAGE THRESHOLD

vs. TEMPERATURE

Junction Temperature (°C)

31

Rev. C 06/15

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TOP232-234

Typical Performance Characteristics (cont.)

MULTI-FUNCTION PIN VOLTAGE

vs. CURRENT

MULTI-FUNCTION PIN VOLTAGE

vs. CURRENT (EXPANDED)

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

6

5

4

3

2

See

Expanded

Version

1

0

-300 -250 -200 -150 -100 -50

0

-300 -200 -100

0

100 200 300 400 500

MULTI-FUNCTION Pin Current (mA)

MULTI-FUNCTION Pin Current (µA)

CONTROL CURRENT at START of

CYCLE SKIPPING vs. TEMPERATURE

MAX. DUTY CYCLE REDUCTION ONSET

THRESHOLD CURRENT vs. TEMPERATURE

Junction Temperature (°C)

I vs. DRAIN VOLTAGE

OUTPUT CHARACTERISTICS

C

1.5

2

V_C= 5 V

T_CASE= 25 °C

T

_CASE= 100 °C

1.6

1.2

1

0.5

0

Scaling Factors:

0.8

0.4

0

TOP234 1.00

TOP233 0.67

TOP232 0.33

0

20

40

60

80

100

0

2

4

6

8

10

DRAIN Voltage (V)

32

Rev. C 06/15

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TOP232-234

Typical Performance Characteristics (cont.)

C

OSS

vs. DRAIN VOLTAGE

DRAIN CAPACITANCE POWER (132 kHz)

1000

Scaling Factors:

300

TOP234 1.00

TOP233 0.67

TOP232 0.33

TOP234 1.00

TOP233 0.67

TOP232 0.33

200

100

10

0

200

400

600

0

200

400

600

DRAIN Voltage (V)

33

Rev. C 06/15

www.power.com

TOP232-234

TO-220-7B

.165 (4.19)

.185 (4.70)

.400 (10.16)

.415 (10.54)

.045 (1.14)

.055 (1.40)

.146 (3.71)

.156 (3.96)

.108 (2.74) REF

.236 (5.99)

.260 (6.60)

.570 (14.48)

REF.

.467 (11.86)

.487 (12.37)

7° TYP.

.670 (17.02)

REF.

.860 (21.84)

.880 (22.35)

.095 (2.41)

.115 (2.92)

.028 (.71)

.032 (.81)

.040 (1.02)

.060 (1.52)

.010 (.25) M

.015 (.38)

.020 (.51)

.040 (1.02)

.060 (1.52)

.050 (1.27) BSC

.150 (3.81) BSC

.190 (4.83)

.210 (5.33)

Notes:

.050 (1.27)

1. Controlling dimensions are inches. Millimeter

dimensions are shown in parentheses.

2. Pin locations start with Pin 1, and continue

from left to right when viewed from the front.

Pins 2 and 6 are omitted.

3. Dimensions do not include mold flash or

other protrusions. Mold flash or protrusions

shall not exceed .006 (.15mm) on any side.

4. Minimum metal to metal spacing at the pack-

age body for omitted pin locations is .068

inch (1.73 mm).

.050 (1.27)

.200 (5.08)

.050 (1.27)

.180 (4.58)

5. Position of the formed leads to be measured

at the mounting plane, .670 inch (17.02 mm)

below the hole center.

.150 (3.81)

MOUNTING HOLE PATTERN

Y07B

6. All terminals are solder plated.

34

Rev. C 06/15

www.power.com

TOP232-234

PDIP-8B (P Package)

⊕

D S .004 (.10)

Notes:

.137 (3.48)

MINIMUM

1. Package dimensions conform to JEDEC specification

MS-001-AB (Issue B 7/85) for standard dual-in-line (DIP)

package with .300 inch row spacing.

-E-

2. Controlling dimensions are inches. Millimeter sizes are

shown in parentheses.

3. Dimensions shown do not include mold flash or other

protrusions. Mold flash or protrusions shall not exceed

.006 (.15) on any side.

.240 (6.10)

.260 (6.60)

4. Pin locations start with Pin 1, and continue counter-clock-

wise to Pin 8 when viewed from the top. The notch and/or

dimple are aids in locating Pin 1. Pin 6 is omitted.

5. Minimum metal to metal spacing at the package body for

the omitted lead location is .137 inch (3.48 mm).

6. Lead width measured at package body.

Pin 1

-D-

7. Lead spacing measured with the leads constrained to be

perpendicular to plane T.

.367 (9.32)

.387 (9.83)

.057 (1.45)

.068 (1.73)

(NOTE 6)

.125 (3.18)

.145 (3.68)

.015 (.38)

MINIMUM

-T-

SEATING

PLANE

.008 (.20)

.015 (.38)

.120 (3.05)

.140 (3.56)

.300 (7.62) BSC

(NOTE 7)

.100 (2.54) BSC

.048 (1.22)

.053 (1.35)

P08B

.300 (7.62)

.390 (9.91)

.014 (.36)

.022 (.56)

⊕

T E D S .010 (.25) M

PI-2551-040110

SMD-8B (G Package)

⊕

D S .004 (.10)

Notes:

.137 (3.48)

MINIMUM

1. Controlling dimensions are

inches. Millimeter sizes are

shown in parentheses.

-E-

2. Dimensions shown do not

include mold flash or other

protrusions. Mold flash or

protrusions shall not exceed

.006 (.15) on any side.

3. Pin locations start with Pin 1,

and continue counter-clock-

wise to Pin 8 when viewed

from the top. Pin 6 is omitted.

4. Minimum metal to metal

spacing at the package body

for the omitted lead location

is .137 inch (3.48 mm).

.372 (9.45)

.388 (9.86)

.240 (6.10)

.260 (6.60)

.420

.010 (.25)

⊕

E S

.046 .060 .060 .046

.080

Pin 1

-D-

5. Lead width measured at

package body.

6. D and E are referenced

datums on the package

body.

.086

.186

.100 (2.54) (BSC)

.286

.367 (9.32)

.387 (9.83)

Solder Pad Dimensions

.057 (1.45)

.068 (1.73)

(NOTE 5)

.125 (3.18)

.145 (3.68)

.004 (.10)

.032 (.81)

.037 (.94)

.048 (1.22)

.053 (1.35)

°

.009 (.23)

0 - 8

.036 (0.91)

.044 (1.12)

.004 (.10)

.012 (.30)

G08B

PI-2546-040110

35

Rev. C 06/15

www.power.com

TOP232-234

Revision

Notes

Date

A

Initial Release.

01/00

Corrected rounding of operating frequency (132/66 kHz), corrected spelling and corrected Storage Temperature θ_JCand

updated nomenclature in parameter table.

B

C

07/01

06/15

Updated with new Brand Style Logo.

For the latest updates, visit our website: www.power.com

Power Integrations reserves the right to make changes to its products at any time to improve reliability or manufacturability. Power

Integrations does not assume any liability arising from the use of any device or circuit described herein. POWER INTEGRATIONS MAKES

NO WARRANTY HEREIN AND SPECIFICALLY DISCLAIMS ALL WARRANTIES INCLUDING, WITHOUT LIMITATION, THE IMPLIED

WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT OF THIRD PARTY RIGHTS.

Patent Information

The products and applications illustrated herein (including transformer construction and circuits external to the products) may be covered

by one or more U.S. and foreign patents, or potentially by pending U.S. and foreign patent applications assigned to Power Integrations.

A complete list of Power Integrations patents may be found at www.power.com. Power Integrations grants its customers a license under

certain patent rights as set forth at http://www.power.com/ip.htm.

Life Support Policy

POWER INTEGRATIONS PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR

SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF POWER INTEGRATIONS. As used herein:

1. A Life support device or system is one which, (i) is intended for surgical implant into the body, or (ii) supports or sustains life, and (iii)

whose failure to perform, when properly used in accordance with instructions for use, can be reasonably expected to result in signiﬁcant

injury or death to the user.

2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause

the failure of the life support device or system, or to affect its safety or effectiveness.

The PI logo, TOPSwitch, TinySwitch, LinkSwitch, LYTSwitch, InnoSwitch, DPA-Switch, PeakSwitch, CAPZero, SENZero, LinkZero,

HiperPFS, HiperTFS, HiperLCS, Qspeed, EcoSmart, Clampless, E-Shield, Filterfuse, FluxLink, StakFET, PI Expert and PI FACTS are

Power Integrations Worldwide Sales Support Locations

World Headquarters

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Japan

Taiwan

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Phone: +49-895-527-39110

Fax: +49-895-527-39200

e-mail: eurosales@power.com

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e-mail: japansales@power.com

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e-mail: taiwansales@power.com

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Main: +1-408-414-9200

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36

Rev. C 06/15

www.power.com


型号：	TOP234YN
厂家：	Power Integrations
描述：	IC OFFLINE SWIT OVP UVLO TO220
文件：	总36页 (文件大小：1767K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

TOP234YN [POWERINT]

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