TOP233Y_技术文档

®

TOP232-234

®

TOPSwitch-FX Family

Design Flexible, EcoSmart^®, Integrated

Off-line Switcher

Product Highlights

+

Lower System Cost, High Design Flexibility

• Features eliminate or reduce cost of external components

AC

IN

DC

OUT

-

• 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

TOPSwitch-FX

• Line feed forward with maximum duty cycle (DC_MAX

)

reduction rejects ripple and limits DC_MAXat high line

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-2503-073099

Figure 1. Typical Flyback Application.

OUTPUT POWER TABLE

• 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

230 VAC 15%

85-265 VAC

PART

ORDER

Open

Adapter¹

1

NUMBER^{3 Adapter}

Frame²

TOP232P

9 W

15 W

6.5 W

10 W

®

EcoSmart - Energy Efficient

TOP232G

• 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

10 W

13 W

20 W

16 W

30 W

25 W

50 W

30 W

75 W

7 W

9 W

15 W

30 W

20 W

45 W

TOP232Y

TOP233P

TOP233G

TOP233Y

TOP234P

TOP234G

TOP234Y

15 W

11 W

20 W

Description

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

anaccuratecurrentlimit. Ineithercase,thispincanalsobeused

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,whichallowsthedevicetooperateinathreeterminal

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.

TOPSwitch mode, but with the following new transparent

features:soft-start,cycleskipping,132 kHzswitchingfrequency,

frequency jittering, wider DC_MAX, hysteretic thermal shutdown

and larger creepage. In addition, all critical parameters such as

frequency,currentlimit,PWMgain,etc.havetightertemperature

and absolute tolerances compared to the TOPSwitch-II family.

HighercurrentlimitaccuracyandlargerDC_MAX,whencombined

with other features allow for a 10% to 15% higher power

capabilityontheTOPSwitch-FXdevicescomparedtoequivalent

TOPSwitch-II devices for the same input/output conditions.

July 2001

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 Under-Voltage 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

B

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TOP232-234

DRAIN (D)

0

1

CONTROL (C)

V

C

Z

C

INTERNAL

SUPPLY

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

HYSTERETIC

THERMAL

SHUTDOWN

MULTI-

FUNCTION (M)

V

BG

CONTROLLED

TURN-ON

GATE DRIVER

STOP

SOFT-

OV/UV

DC

START

D

LINE

SENSE

MAX

DC

MAX

CLOCK

SAW

S

R

Q

HALF

-

LEADING

EDGE

BLANKING

FREQUENCY

FREQUENCY (F)

(Y Package Only)

+

OSCILLATOR WITH JITTER

PWM

COMPARATOR

R

E

SOURCE (S)

PI-2535-083099

Figure 2. Functional Block Diagram.

The switching frequency is internally set for 132 kHz only

operation in P and G packages.

Pin Functional Description

DRAIN (D) Pin:

SOURCE (S) Pin:

Output MOSFET source connection for high voltage power

return. Primary side control circuit common and reference point.

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.

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 F

4 S

3 M

1 C

Y Package (TO-220-7B)

MULTI-FUNCTION (M) Pin:

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

externalsetcurrentlimit,remoteON/OFFandsynchronization.

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

S

7 S

3

S

C 4

5 D

FREQUENCY (F) Pin: (Y package only)

Inputpinforselectingswitchingfrequency:132 kHzifconnected

to SOURCE pin and 66 kHz if connected to CONTROL pin.

P Package (DIP-8B)

G Package (SMD-8B)

PI-2501-031901

Figure 3. Pin Configuration.

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TOP232-234

TOPSwitch-FX Family Functional Description

Like TOPSwitch, TOPSwitch-FX is an integrated switched

Auto-restart

I_CD1

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

powerMOSFET. Duringnormaloperationthedutycycleofthe

powerMOSFETdecreaseslinearlywithincreasingCONTROL

pin current as shown in Figure 4.

I_B

78

47

Slope = PWM Gain

InadditiontothethreeterminalTOPSwitchfeatures,suchasthe

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

compensation circuitry, auto-restart, thermal shutdown, etc.,

theTOPSwitch-FX incorporatesmanyadditionalfunctionsthat

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

= 140 µA

M

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)

andMULTI-FUNCTION, havebeenaddedtoimplementsome

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, theTOPSwitch-FXoffersmanynewtransparentfeatures

that do not require any external components:

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.

TheFREQUENCYpinintheTO-220packagesetstheswitching

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.

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.

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

feedbacksignalfromthesupplycurrent.CONTROLpinvoltage

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.

5. Frequency jittering reduces EMI.

6. Hysteretic over-temperature shutdown ensures automatic

recoveryfromthermalfault.Largehysteresispreventscircuit

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

duringstart-up,theMOSFETisinitiallyoff,andtheCONTROL

pincapacitorischargedthroughaswitchedhighvoltagecurrent

sourceconnectedinternallybetweentheDRAINandCONTROL

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

currentisfedintotheCONTROLpinbytheendofthesoft-start,

thehighvoltagecurrentsourceisturnedoffandtheCONTROL

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

8. Tighter absolute tolerances and smaller temperature vari-

ations on switching frequency, current limit and PWM gain.

TheMULTI-FUNCTIONpinisusuallyusedforlinesensingby

connecting a resistor from this pin to the rectified DC high

voltagebustoimplementlineover-voltage(OV)/under-voltage

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

mode,thevalueoftheresistordeterminestheOV/UVthresholds

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

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TOP232-234

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

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.

Oscillator and Switching Frequency

Theinternaloscillatorlinearlychargesanddischargesaninternal

capacitance between two voltage levels to create a sawtooth

waveformforthepulsewidthmodulator. Theoscillatorsetsthe

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

videoapplicationsorahighefficiencystandbymode. Otherwise,

theFREQUENCYpinshouldbeconnectedtotheSOURCEpin

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

preventstheflowofanexternalcurrentintotheCONTROLpin,

the capacitor on the CONTROL pin discharges towards 4.8 V.

At4.8Vauto-restartisactivatedwhichturnstheoutputMOSFET

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

effectivelylimitsTOPSwitch-FXpowerdissipationbyreducing

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

effectofswitchingnoiseinthechipsupplycurrentgeneratedby

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 .

B

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TOP232-234

the MOSFET gate driver. The filtered error signal is compared

with the internal oscillator sawtooth waveform to generate the

dutycyclewaveform. Asthecontrolcurrentincreases, theduty

cycle decreases. A clock signal from the oscillator sets a latch

whichturnsontheoutputMOSFET. Thepulsewidthmodulator

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.

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 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

thetypicalperformancecharacteristicssectionfortheselection

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

techniquereducesmaximumclampvoltageathighlineallowing

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

CONTROLpincurrentincreases,thedutycyclereduceslinearly

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

outputconsumeslesspowerthanthepowerthatTOPSwitch-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.

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.

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.

Error Amplifier

The shunt regulator can also perform the function of an error

amplifierinprimaryfeedbackapplications. Theshuntregulator

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

todynamiccharacteristicsoftheMOSFET. Toavoidtriggering

thecurrentlimitinnormaloperation,thedraincurrentwaveform

should stay within the envelope shown.

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

Line Under-Voltage Detection (UV)

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

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TOP232-234

voltage reaches the under-voltage threshold. At power down,

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

regulation. This eliminates power down glitches caused by the

slowdischargeofinputstoragecapacitorpresentinapplications

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 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.

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

alsoreducedfrom78%(typical)atavoltageslightlyhigherthan

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.

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

Figure8). ThisallowseasyimplementationofremoteON/OFF

controlofTOPSwitch-FXinseveraldifferentways. Atransistor

or an optocoupler output connected between the MULTI-

FUNCTIONpinandtheSOURCEpinimplementsthisfunction

with“active-on”(Figure19)whileatransistororanoptocoupler

outputconnectedbetweentheMULTI-FUNCTIONpinandthe

CONTROL pin implements the function with “active-off”

(Figure 20).

Line Overvoltage Shutdown (OV)

ThesameresistorusedforUValsosetsanovervoltagethreshold

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,

therectifiedDChighvoltagesurgecapabilityisincreasedtothe

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

the reflected voltage and leakage spikes on the drain. Small

amountofhysteresisisprovidedontheOVthresholdtoprevent

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

Oscillator

(SAW)

D

MAX

Enable from

M Pin (STOP)

Time

PI-2558-092999

Figure 7. Synchronization Timing Diagram.

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TOP232-234

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-FXis held

inremoteoffstateforlongenoughtimetoallowtheCONTROL

pin to dishcharge to the internal supply under-voltage 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

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

eliminateexpensiveandunreliablein-linemechanicalswitches.

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.

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-

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

temperatureexceedsthethermalshutdowntemperature(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

All critical TOPSwitch-FX internal voltages are derived from a

temperature-compensatedbandgapreference. Thisreferenceis

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

lineOV/UVthresholds. TOPSwitch-FXhasimprovedcircuitry

to maintain all of the above critical parameters within very tight

absolute and temperature tolerances.

Soft-Start

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

whenrestartingafterbeinginhystereticregulationofCONTROL

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

outputrectifier,duringstart-up. Thisfeaturealsohelpsminimize

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

duringauto-restart,remoteoffandover-temperatureshutdown.

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

isturnedoffduringnormaloperationwhentheoutputMOSFET

is switching.

Shutdown/Auto-Restart

To minimize TOPSwitch-FX power dissipation under fault

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

B

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8

TOP232-234

Using FREQUENCY and MULTI-

FUNCTION Pins

FREQUENCY (F) Pin Operation

for line sensing by connecting a resistor from this pin to the

rectifiedDChighvoltagebustoimplementOV,UVandDC_MAX

reduction 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.

PleaserefertoTable2forpossiblecombinationsofthefunctions

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

thosethatcontroltheon/offstatesoftheoutputsuchasUV, 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

currentlimitisavailableonlywithnegativeMULTI-FUNCTION

pin current. Please see graphs in the typical performance

characteristics section for the current limit programming range

and the selection of appropriate resistor value.

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

lowertheswitchingfrequencyfrom132kHzinnormaloperation

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

MULTI-FUNCTION PIN TABLE*

Figure Number

13

14

15

16

17

18

19

20

21

22

23

✔

Three Terminal Operation

Under-Voltage

✔

Overvoltage

✔

Line Feed Forward (DC_MAX

)

Line Feed Forward (I_LIMIT

)

✔

External Current Limit

Remote ON/OFF

✔

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

Table 2. Typical MULTI-FUNCTION Pin Configurations.

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9

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 - Under-Voltage,

Over-Voltage, Maximum Duty

Cycle Reduction)

400 µA

PI-2548-092399

Figure 9. MULTI-FUNCTION Pin Input Simplified Schematic.

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10

TOP232-234

Typical Uses of FREQUENCY (F) Pin

+

DC

Input

Voltage

DC

Input

D

S

D

CONTROL

F

CONTROL

Voltage

C

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).

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11

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

R_LS

2 MΩ

DC

Input

DC

Input

V

_OV= 450 VDC

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 14. Line Sensing for Under-Voltage, Overvoltage and

Maximum Duty Cycle Reduction.

Figure 13. Three Terminal Operation (MULTI-FUNCTION

Features Disabled. FREQUENCY Pin Tied to SOURCE

or CONTROL Pin).

+

V_UV= R_LSx I_UV

V_OV= I_OVx R_LS

2 MΩ

For Value Shown

R_LS

For Values Shown

R_LS

V

_UV= 100 VDC

V

_OV= 450 VDC

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 Under-Voltage Only (Overvoltage

Disabled).

Figure 16. Line Sensing for Overvoltage Only (Under-Voltage

Disabled).

+

For R_IL= 12 kΩ

I_LIMIT= 90% @ 100 VDC

I_LIMIT= 67%

I_LIMIT

=

R_LS2.5 MΩ

55% @ 300 VDC

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.

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12

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

47 kΩ

DC

Input

Voltage

DC

Input

Voltage

ON/OFF

R_MC

45 kΩ

M

D

S

M

D

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.

For R_IL= 12 kΩ

Q_R

ON/OFF

I_LIMIT= 67 %

DC

Input

DC

Input

Voltage

47 kΩ

For R_IL= 25 kΩ

Voltage

R_MC

24 kΩ

R_MC= 2R_IL

I_LIMIT= 40 %

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-2523-040401

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

B

7/01

13

TOP232-234

reflected voltage, by safely limiting the TOPSwitch-FX drain

voltage, with adequate margin, under worst case conditions.

The extended maximum duty cycle feature of TOPSwitch-FX

(guaranteedminimumvalueof75%vs. 64%forTOPSwitch-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

jitterprovidesimprovedmarginforconductedEMImeetingthe

CISPR 22 (FCC B) specification.

Application Examples

A High Efficiency, 30 W, Universal Input Power Supply

ThecircuitshowninFigure24takesadvantageofseveralofthe

TOPSwitch-FXfeaturestoreducesystemcostandpowersupply

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

approximately70%ofthedefaultcurrentlimit. Thisallowsuse

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

signalthatreducesthecurrentlimitwithincreasinglinevoltage,

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

input line voltage. The feed forward function in combination

with the built-in soft-start feature ofTOPSwitch-FX, allows the

use of a low cost RCD clamp (R3, C3 and D1) with a higher

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

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

voltagedropsacrosstheoptocoupler (U2)LEDandresistorR6.

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.

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

D2

1N4148

R1

4.7 MΩ

1/2 W

R6

150 Ω

L1

20 mH

R8

C6

100 nF

150 Ω

T1

C1

U2

LTV817A

CX1

100 nF

68 µF

D

S

M

TOPSwitch-FX

400 V

U1

CONTROL

250 VAC

C

TOP234Y

R5

6.8 Ω

R2

F

F1

3.15 A

VR2

1N5240C

10 V, 2%

9.09 kΩ

J1

L

C5

47 µF

10 V

N

PI-2525-040401

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

B

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14

TOP232-234

35 W Multiple Output Power Supply

pin instead of the SOURCE pin in video noise sensitive

applications to allow for heavier snubbing without significant

impact on efficiency.

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

powersupplyutilizingaTOP233formultipleoutputapplications

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

designedfora230VACinputbutcanbeusedovertheuniversal

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

outputsusingdualsensedoptocouplerfeedbackthroughresistors

R9,R10andR11.Otheroutputvoltagesaresetbythetransformer

turnsratio. Outputvoltageonthelowpower-5Voutputisshunt

regulated by resistor R12 and Zener diode VR2. Dummy load

resistor R13 is required to maintain regulation of the 30 V

outputunderlightloadconditions. CompensationoftheTL431

(U3) is achieved with resistor R8 and capacitor C7. Primary

side compensation and auto-restart frequency are determined

byresistorR5andcapacitorC5. SecondstageLCpost-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-

voltagedetect(at100V), over-voltageshutdown(at450V)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,

maintainingemissionsbelowCISPR22(FCCB)levelsthrough

properchoiceofY1capacitor(CY1)andinputfilteringelements

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

totheTOP233, Y1capacitoristiedtothepositiveinputDCrail.

Lightning strike immunity to 3 kV is attained with the addition

of a 275 V MOV (RV1).

Thisdesignalsotakesadvantageofsoft-startandhigheroperating

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-FXcan

beusedbyconnectingtheFREQUENCYpintotheCONTROL

30 V

@ 100 mA

C11

D8

MUR120

C10

L2

3.3 µH

1 µF

100 µF

18 V

@ 550 mA

50 V

C12

220 µF

25 V

D9

UF5402

C13

100 µF

25 V

R13

24 kΩ

CY1

2.2 nF

L3

3.3 µH

5 V

@ 2.5 A

D10

MBR1045

C14

C15

100 µF

10 V

1000 µF

L4

3.3 µH

3.3 V

@ 3 A

25 V

VR1

P6KE200

D11

BYW29-

100

C16

C17

100 µF

10 V

1000 µF

25 V

D1

UF4007

BR1

400 V

RTN

C18

C19

330 µF

VR2

1N5231

D12

1N5819

R12

5 Ω

-5 V

100 µF

10 V

@ 100 mA

10 V

C1

L1

20 mH

33 µF

400 V

D2

1N4148

R6

51 Ω

R10

15.0 kΩ

R1

2 MΩ

U2

LTV817

T1

R7

510 Ω

1/2 W

CX1

0.1 µF

250 VAC

C4

C6

100 nF

R9

9.53 kΩ

47 pF

TOPSwitch-FX

D

S

M

R4

2 kΩ

CONTROL

C7

R8

F1

3.15 A

C

10 Ω 0.1 µF

TOP233Y

U1

R5

6.8 Ω

F

J1

U3

TL431CLP

C5

47 µF

C8

22 µF

L

RV1

275 V

R11

10.0 kΩ

N

PI-2536-040401

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

B

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15

TOP232-234

achieved by turning the power supply off when the input

voltagegoesbelowalevelneededtomaintainoutputregulation

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 200VDC, slightly below

the required lowest operating DC input voltage, for start-up at

170VAC. This feature saves several components needed to

implement the glitch free turn off with discrete or

TOPSwitch-II based designs.

17 W PC Standby Power Supply

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

andhigherswitchingfrequencyfeaturesofTOPSwitch-FX. For

example, the higher switching frequency with tighter current

limit variation allows use of an EE19 transformer core.

Furthermore, thespacingbetweenhighvoltageDRAINpinand

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 15V primary

bias output voltage for the main power supply primary control

circuitry. Both 3.3V and 5V 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

biascurrentfortheTL431whentheoptocouplerisataminimum

current. CapacitorC8providesasoft-finishfunctiontoeliminate

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 under-voltage. 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. This is

CY1

1 nF

L1

3.3 µH

5 V

C10

1000 µF

10 V

C11

100 µF

10 V

@ 2 A

D3

L2

3.3 µH

+

SB540

VR1

BZY97C-200

3.3 V

@ 2 A

C12

1000 µF

10 V

C13

100 µF

10 V

D4

SB540

R1

200-375

VDC

3.9 MΩ

RTN

D1

UF4005

15 V

D2

BAV21

@ 30 mA

R6

301 Ω

(Primary

Referenced)

C1

R7

0.01 µF

C6

35 V

510 Ω

T1

1 kV

R9

16.2 kΩ

(optional)

U2

SFH615-2

D

M

TOPSwitch-FX

U1

TOP232Y

R10

12.1 kΩ

CONTROL

C

C7

R5

6.8 Ω

0.1 µF

S

F

C8

10 µF

35 V

U3

TL431CLP

R11

10 kΩ

C5

47 µF

-

PI-2537-040401

Figure 26. 17 W PC Standby Supply.

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TOP232-234

Processor Controlled Supply Turn On/Off

may include safely parking the print heads in the storage

position. Inthecaseofproductswithadiskdrive, theshutdown

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

capacitorC_Mmaybeneededtopreventnoisecouplingtothepin

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

lowpowerremoteofffeatureallowsanelegantimplementation

of this function with very few external components as shown in

Figure27.Wheneverthepushbuttonmomentarycontactswitch

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 microprocessor comes

alive and recognizes that the switch P1 is closed through the

switch status input that is driven by the optocoupler U3 output.

Themicroprocessorthensendsapowersupplycontrolsignalto

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,inthecaseoftheinkjetprinter,theshutdownprocedure

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,externalmodems,diskdrives,etc.,asneeded

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

U2

27 kΩ

1N4148

LOGIC LOGIC

INPUT OUTPUT

1N4148

6.8 kΩ

TOPSwitch-FX

D

S

M

U4

CONTROL

C

U3

6.8 kΩ

C_M

1 nF

47 µF

F

U1

U3

LTV817A

P1

P1 Switch

Status

U4

LTV817A

-

RETURN

PI-2561-040401

Figure 27. Remote ON/OFF Using Microcontroller.

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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:

sequence when it detects the first closure of the switch, and

subsequentbouncingoftheswitchhasnoeffect. Ifnecessary,

the microprocessor could implement the switch debouncing

in software during turn-off, or a filter capacitor can be used

at the switch status input.

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.

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.

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

switch can be used.

3. Nodebouncingcircuitryforthemomentaryswitchisrequired.

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 shutdown

6. Robustdesign:Thereisnoon/offlatchthatcanbeaccidentally

triggered by transients. Instead, the power supply is held in

the on-state through the secondary side microprocessor.

B

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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,

• Smaller transformer

18, 21, • Higher efficiency

22

4

• Allows tighter power limit

during output overload conditions

DC_MAX

78%

• 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 N/A*

DC_MAXReduction

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 cap-

ability against line surge

N/A*

Single resistor

programmable

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

15, 23

during 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 6, 28

2 kHz@66 kHz

• Reduces conducted EMI

At DC_MIN(1.5%)

4

• 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)

B

7/01

19

TOP232-234

Function

TOPSwitch-II

TOPSwitch-FX Figures Advantages

Remote ON/OFF

N/A*

Single transistor

or optocoupler

8, 19,

• Fast on/off (cycle by cycle)

20, 21, • Active-on or active-off control

interface or manual 22, 23, • Low consumption in remote off state

switch

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

Latched

Hysteretic (with

70 °C hysteresis)

• Automatic recovery from thermal

fault

• Large hysteresis prevents circuit

board overheating

Current Limit Tolerance 10% (@25 °C)

7% (@25 °C)

• 10% higher power capability due to

tighter tolerance

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

DRAIN

Creepage at

Package

DIP

SMD

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

TO-220 0.046" / 1.17 mm

DRAIN Creepage at

PCB for TO-220

0.045" / 1.14 mm

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

DCvoltagerequiredfortheTOPSwitch-FXconvertertomaintain

regulation at the lowest specified input voltage and maximum

output power. Since TOPSwitch-FX has a higher DC_MAXthan

TOPSwitch-II,itispossibletouseasmallerinputcapacitor. For

TOPSwitch-FX, a capacitance of 2 µF per watt is usually

sufficient for universal input with an appropriately designed

transformer.

AhighV_ORisrequiredtotakefulladvantageofthewiderDC_MAX

of TOPSwitch-FX. An RCD clamp provides tighter clamp

voltage tolerance than a Zener clamp and allows a V_ORas high

as165V. TheV_ORcanbe furtherincreasedincontinuousmode

designs up to 185 V by reducing the external current limit as a

function of input line voltage (see Figure 18). The RCD clamp

B

7/01

20

TOP232-234

12

10

8

is more cost effective than the Zener clamp but requires more

careful design (see quick design checklist).

Average

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).

6

4

Quasi-Peak

2

Soft-Start

0

2nd

3rd

4th

5th

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-FXMOSFET,

clampcircuitandoutputdiode(s),andhelpspreventtransformer

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)

20

-10

0

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. AscanbeseeninFigure28, thebenefitsofjitterincrease

with the order of the switching harmonic due to an increase in

frequency deviation.

VFG243B (QP)

VF646B (AV)

-10

-20

0.15

1

10

30

Frequency (MHz)

(b)

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

at66kHzwillreducesnubberlossresultinginbetterefficiency.

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.

80

70

60

TOPSwitch-FX (with jitter)

50

40

30

20

-10

0

VFG243B (QP)

VF646B (AV)

For10Worbelow,itispossibletouseasimpleinductorinplace

of a more costly AC input common mode choke to meet

worldwide conducted EMI limits.

-10

-20

0.15

1

10

30

Frequency (MHz)

Transformer Design

(c)

Itisrecommendedthatthetransformerbedesignedformaximum

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

Figure 28. (a) Conducted noise improvement for low frequency

harmonics due to jitter, (b) TOPSwitch-II full range EMI

scan (100kHz, no jitter), (c) TOPSwitch-FX full range

EMI scan (132 kHz, with jitter) with identical circuitry

and conditions.

B

7/01

21

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-2543-092199

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

Maximize hatched copper

Safety Spacing

areas (

) for optimum

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-2544-092199

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

B

7/01

22

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.

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

nodes on the PC board.

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,thetightercurrentlimittolerance,higherswitching

frequency and soft-start features of TOPSwitch-FX contribute

to a smaller transformer when compared to TOPSwitch-II.

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

underneaththepackageconnectedtotheSOURCEpinswillact

as an effective heat sink.

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

Standby Consumption

Cycleskippingcansignificantlyreducepowerlossatzeroload,

especially when a Zener clamp is used. For very low secondary

powerconsumptionuseaTL431regulatorforfeedbackcontrol.

Alternately, switching losses can be significantly reduced by

switching from 132 kHz in normal operation to 66 kHz under

light load conditions.

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

exceed675Vathighestinputvoltageandmaximumoverload

output power. Maximum overload output power occurs

whentheouputisoverloadedtoaleveljustbeforethepower

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

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.

2. Maximumdraincurrent–Atmaximumambienttemperature,

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.

TheCONTROLpinbypasscapacitorshouldbelocatedasclose

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

SOURCEandMULTI-FUNCTIONpinswithdedicatedSOURCE

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.

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 heatsink, 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.

Inadditiontothe47µFCONTROLpincapacitor,ahighfrequency

bypasscapacitorinparallelmaybeusedforbetternoiseimmunity.

The feedback optocoupler output should also be located close to

the CONTROL and SOURCE pins of TOPSwitch-FX.

Y-Capacitor

Design Tools

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).

1. Technical literature: Data Sheet, Application Notes,

Design Ideas, etc.

2. Transformer design spreadsheet.

3. Engineering prototype boards.

Heat Sinking

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

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

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

Integrations Web site: www.powerint.com

B

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23

TOP232-234

ABSOLUTE MAXIMUM RATINGS⁽¹⁾

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

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

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

Storage Temperature ..................................... -65 to 150 °C

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

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

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

Notes:

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

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

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

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

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

2. Normally limited by internal circuitry.

3. 1/16" from case for 5 seconds.

THERMAL IMPEDANCE

Thermal Impedance: Y Package (θ_JA)⁽¹⁾............... 70 °C/W

Notes:

(θ_JC)⁽²⁾................. 2 °C/W

1. Free standing with no heatsink.

2. Measured at the back surface of tab.

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

4. Soldered to 1 sq. inch (645 mm²), 2oz. (610 gm/m²) copper clad.

5. Measured on the SOURCE pin close to plastic interface.

P/G Package:

(θ_JA) ........ 45 °C/W⁽³⁾; 35 °C/W⁽⁴⁾

(θ_JC)⁽⁵⁾.......................... 11 °C/W

Conditions

(Unless Otherwise Specified)

See Figure 34

Parameter

Symbol

Min

Typ Max

Units

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

132 kHz Operation

66 kHz Operation

4

2

Frequency Jitter

Deviation

∆f

Frequency Jitter

f_M

250

Hz

%

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

0.8

1.5

2.7

Cycle (Prior to

%

Cycle Skipping)

t_SOFT

ms

T_J= 25 °C; DC_MINto DC_MAX

10

14

Soft Start Time

PWM

Gain

-27

-22

-17

%/mA

I_C= 4 mA; T_J= 25 °C

B

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24

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

5.9

15

%/mA/°C

See Note A

Temperature Drift

External Bias

Current

l_B

mA

See Figure 4

1.2

10

2.8

7.5

22

CONTROL

Current at Start of

Cycle Skipping

T_J= 25 °C

mA

Ω

Dynamic

Impedance

I_C= 4 mA; T_J= 25 °C

Z_C

See Figure 32

Dynamic

Impedance

0.18

7

%/°C

kHz

Temperature Drift

Control Pin

Internal Filter Pole

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

l_{C (CH)}

mA

T_J= 25 °C

Charging Current

Temperature Drift

See Note A

0.5

5.8

4.8

1.0

4

%/°C

Auto-restart Upper

v_C(AR)

V

Threshold Voltage

Auto-restart Lower

Threshold Voltage

4.5

0.8

2

5.1

8

Auto-restart

Hysteresis Voltage

V

Auto-restart Duty

Cycle

%

Hz

Auto-restart

Frequency

1.0

B

7/01

25

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 Under-Voltage

l_UV

T_J= 25 °C

µA

44

50

225

10

54

Threshold Current

Line Over-Voltage

or Remote ON/

OFF Threshold

µA

Threshold

210

240

I_OV

T_J= 25 °C

Current and

Hysteresis

Remote ON/OFF

Threshold

-43

-35

-7

-27

µA

I_{REM (N)}

Negative Threshold

Current and

T_J= 25 °C

Hysteresis

V_M= V_C

Hysteresis

300

-300

-110

400

-240

-90

520

-180

-70

MULTI-FUNCTION

Pin Short Circuit

Current

I_{M (SC)}

Normal Mode

V_M= 0 V

µA

Auto-restart Mode

l_M= 50 µA

l_M= 225 µA

l_M= -50 µA

2.00

2.50

1.25

1.18

2.60

2.90

1.32

1.24

3.00

3.30

1.39

1.30

MULTI-FUNCTION

Pin Voltage

V

V_M

l_M= -150 µA

Maximum Duty

Cycle Reduction

Onset Threshold

Current

I_{M (DC)}

T_J= 25 °C

µA

%/µA

mA

75

90

110

Maximum Duty

Cycle Reduction

Slope

I_M> I_{M (DC)}

0.30

MULTI-FUNCTION

Pin Floating

0.6

1.0

2.5

1.1

1.8

4.0

Remote OFF

DRAIN Supply

Current

V_DRAIN= 150 V

MULTI-FUNCTION

Pin Shorted to

CONTROL

From Remote On to Drain Turn-On

See Note B

µs

T_RON

1.5

Remote ON Delay

Minimum Time Before Drain

Turn-On to Disable Cycle

Remote OFF

Setup Time

2.5

4.0

T_ROFF

See Note B

B

7/01

26

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

1.0

10

2.9

22

V_C-1.0

40

V

V_F

I_F

See Note B

V_F= V_C

FREQUENCY Pin

Input Current

µA

CIRCUIT PROTECTION

TOP232

T_J= 25 °C

Internal; di/dt = 100mA/µs

See Note C

0.465

0.930

1.395

0.500

1.000

1.500

0.535

1.070

1.605

TOP233

T_J= 25 °C

Internal; di/dt = 200mA/µs

Self Protection

Current Limit

I_LIMIT

A

See Note C

Internal; di/dt = 300mA/µs

See Note C

TOP234

T_J= 25 °C

≤ 85 VAC

0.75 x

I_LIMIT(MIN)

(Rectified Line Input)

See Figure 33

I_INIT

Initial Current Limit

T_J= 25 °C

265 VAC

(Rectified Line Input)

0.6 x

I_LIMIT(MIN)

Leading Edge

Blanking Time

t_LEB

t_ILD

I_C= 4 mA

ns

°C

200

100

135

Current Limit Delay

I_C= 4 mA

Thermal Shutdown

Temperature

125

2.0

150

4.3

Thermal Shutdown

Hysteresis

70

°C

Power-up Reset

Threshold Voltage

3.3

V_C(RESET)

V

Figure 34, S1 open

OUTPUT

T_J= 25 °C

TOP232

I_D= 50 mA

15.6

25.7

7.8

18.0

30.0

9.0

T_J= 100 °C

T_J= 25 °C

T_J= 100 °C

T_J= 25 °C

T_J= 100 °C

TOP233

I_D= 100 mA

ON-State

Resistance

R_DS(ON)

Ω

12.9

5.2

15.0

6.0

TOP234

I_D= 150 mA

8.6

10.0

B

7/01

27

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_M= Floating; I_C= 4mA

I_D= 100 µA; T_J= 25 °C

Breakdown

Voltage

700

V

BV_DSS

t_R

Rise

Time

ns

100

50

Measured in a Typical

Flyback Converter Application

Fall

Time

ns

V

t_F

SUPPLY VOLTAGE CHARACTERISTICS

DRAIN Supply

Voltage

36

See Note D

Shunt Regulator

Voltage

V_C(SHUNT)

V

5.60

5.85

50

6.10

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

Resistance) 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.

B

7/01

28

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

120

100

80

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

I

@ 85 VAC

INIT(MIN)

60

I

@ 265 VAC

INIT(MIN)

40

I

@ 25 °C

LIMIT(MAX)

LIMIT(MIN)

Dynamic

Impedance

1

=

Slope

20

0

2

4

6

8

10

0

1

2

3

4

5

6

7

8

CONTROL Pin Voltage (V)

Time (us)

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

CONTROL

470 Ω

C

TOPSwitch-FX

S2

F

S

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-2538-040401

Figure 34. TOPSwitch-FX General Test Circuit.

B

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29

TOP232-234

BENCH TEST PRECAUTIONS FOR EVALUATION OF ELECTRICAL CHARACTERISTICS

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_Cpower 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-FXbyitselfoutsideofapowersupply.Theschematic

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-restartmode. TheCONTROLpinvoltagewillbeoscillating

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 while in this auto-

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

0

5K

10K

15K

20K

25K

30K

External Current Limit Resistor R_IL(Ω)

B

7/01

30

TOP232-234

Typical Performance Characteristics (cont.)

BREAKDOWN vs. TEMPERATURE

FREQUENCY vs. TEMPERATURE

1.2

1.0

0.8

0.6

0.4

1.1

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)

INTERNAL CURRENT LIMIT

vs. TEMPERATURE

EXTERNAL CURRENT LIMIT vs.

TEMPERATURE with R_IL= 12 kΩ

1.2

1.0

0.8

1.0

0.8

0.6

0.4

0.2

0.6

Scaling Factors:

TOP234 1.50

TOP233 1.00

TOP232 0.50

0.4

0.2

0

-50 -25

0

25 50 75 100 125 150

-50 -25

0

25 50 75 100 125 150

Junction Temperature (°C)

UNDER-VOLTAGE THRESHOLD

vs. TEMPERATURE

OVER-VOLTAGE THRESHOLD

vs. TEMPERATURE

1.2

1.0

0.8

0.6

0.4

0.2

0

0.8

0.6

0.4

0.2

0

-50 -25

0

25 50 75 100 125 150

-50 -25

0

25 50 75 100 125 150

Junction Temperature (°C)

B

7/01

31

TOP232-234

Typical Performance Characteristics (cont.)

MULTI-FUNCTION PIN VOLTAGE

vs. CURRENT

MULTI-FUNCTION PIN VOLTAGE

vs. CURRENT (EXPANDED)

6

5

4

3

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

2

See

Expanded

Version

1

0

-300 -200 -100

0

100 200 300 400 500

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

0

MULTI-FUNCTION Pin Current (µA)

CONTROL CURRENT at START of

CYCLE SKIPPING vs. TEMPERATURE

MAX. DUTY CYCLE REDUCTION ONSET

THRESHOLD CURRENT vs. TEMPERATURE

1.2

1.0

0.8

0.6

0.4

0.2

1.2

1.0

0.8

0.6

0.4

0.2

0

-50 -25

0

25 50 75 100 125 150

-50 -25

0

25 50 75 100 125 150

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)

B

7/01

32

TOP232-234

Typical Performance Characteristics (cont.)

C

vs. DRAIN VOLTAGE

DRAIN CAPACITANCE POWER (132 kHz)

OSS

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)

B

7/01

33

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)

PIN 1 & 7

PIN 4

.028 (.71)

.032 (.81)

.040 (1.02)

.060 (1.52)

PIN 1

.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)

PIN 1

PIN 7

.150 (3.81)

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.

PI-2560-033001

B

7/01

34

TOP232-234

DIP-8B

⊕

D S .004 (.10)

Notes:

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.

.245 (6.22)

.255 (6.48)

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-

.375 (9.53)

.385 (9.78)

7. Lead spacing measured with the leads constrained to be

perpendicular to plane T.

.057 (1.45)

.063 (1.60)

(NOTE 6)

.128 (3.25)

.132 (3.35)

0.15 (.38)

MINIMUM

-T-

SEATING

PLANE

.010 (.25)

.015 (.38)

.125 (3.18)

.135 (3.43)

.300 (7.62) BSC

(NOTE 7)

.100 (2.54) BSC

.048 (1.22)

.053 (1.35)

T E D S .010 (.25) M

P08B

.300 (7.62)

.390 (9.91)

.014 (.36)

.022 (.56)

⊕

PI-2551-033001

SMD-8B

Notes:

Heat Sink is 2 oz. Copper

As Big As Possible

⊕

D S .004 (.10)

1. Controlling dimensions are

inches. Millimeter sizes are

shown in parentheses.

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

Pin 8 when viewed from the

top. Pin 6 is omitted.

-E-

.372 (9.45)

.388 (9.86)

.245 (6.22)

.255 (6.48)

.420

.010 (.25)

⊕

E S

.046 .060 .060 .046

4. Minimum metal to metal

spacing at the package body

for the omitted lead location

is .137 inch (3.48 mm).

5. Lead width measured at

package body.

6. D and E are referenced

datums on the package

body.

.080

Pin 1

-D-

.086

.186

.286

.100 (2.54) (BSC)

.375 (9.53)

.385 (9.78)

Solder Pad Dimensions

.057 (1.45)

.063 (1.60)

(NOTE 5)

.128 (3.25)

.132 (3.35)

.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-2546-040501

B

7/01

35

TOP232-234

Revision

Notes

Date

1/00

-

A

B

1) Corrected rounding of operating frequency (132/66 kHz).

2) Corrected spelling.

7/01

3) Corrected Storage Temperature θ_JCand updated nomenclature in parameter table.

For the latest updates, visit our Web site: www.powerint.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, nor does it

convey any license under its patent rights or the rights of others.

The PI Logo, TOPSwitch, TinySwitch and EcoSmart are registered trademarks of Power Integrations, Inc.

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Power Integrations, Inc.

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International Holdings, Inc.

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Chung Hsiao E. Rd.,

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International Holdings, Inc.

Rm# 1705, Bao Hua Bldg.

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Phone:

Fax:

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B

7/01

36


型号：	TOP233Y
厂家：	POWER ANALOG MICOELECTRONICS
描述：	TOPSwitch-FX Family Design Flexible, EcoSmartÂ®, Integrated Off-line Switcher 的TOPSwitch - FX系列设计灵活， EcoSmartÂ® ，集成离线式开关开关
文件：	总36页 (文件大小：644K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

TOP233Y [PAM]

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