LNK302D [POWERINT]
Lowest Component Count, Energy-Efficient Off-Line Switcher IC; 最低的元件数量，节能离线式开关IC
| 型号： | LNK302D |
| 厂家： | 
Power Integrations |
| 描述： | Lowest Component Count, Energy-Efficient Off-Line Switcher IC |
| 文件： | 总20页 (文件大小：712K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LNK302/304-306
®
LinkSwitch-TN Family
Lowest Component Count, Energy-Efficient
Off-Line Switcher IC
Product Highlights
Cost Effective Linear/Cap Dropper Replacement
•
•
Lowest cost and component count buck converter solution
Fully integrated auto-restart for short-circuit and open
loop fault protection – saves external component costs
LNK302 uses a simplified controller without auto-restart
for very low system cost
66 kHz operation with accurate current limit – allows low cost
off-the-shelf 1 mH inductor for up to 120 mA output current
Tight tolerances and negligible temperature variation
High breakdown voltage of 700 V provides excellent
input surge withstand
FB
BP
S
D
+
+
•
•
Wide Range
HV DC Input
DC
LinkSwitch-TN
Output
PI-3492-111903
•
•
Figure 1. Typical Buck Converter Application (See Application
Examples Section for Other Circuit Configurations).
•
•
Frequency jittering dramatically reduces EMI (~10 dB)
– minimizes EMI filter cost
High thermal shutdown temperature (+135 °C minimum)
OUTPUT CURRENT TABLE1
230 VAC ±15%
MDCM2 CCM3 MDCM2 CCM3
LNK302P/G/D 63 mA 80 mA 63 mA 80 mA
85-265 VAC
PRODUCT4
Much Higher Performance over Discrete Buck and
Passive Solutions
•
•
Supports buck, buck-boost and flyback topologies
System level thermal overload, output short-circuit and
open control loop protection
LNK304P/G/D 120 mA 170 mA 120 mA 170 mA
LNK305P/G/D 175 mA 280 mA 175 mA 280 mA
LNK306P/G/D 225 mA 360 mA 225 mA 360 mA
•
Excellent line and load regulation even with typical
configuration
•
•
•
•
•
•
•
High bandwidth provides fast turn-on with no overshoot
Current limit operation rejects line ripple
Universal input voltage range (85 VAC to 265 VAC)
Built-in current limit and hysteretic thermal protection
Higher efficiency than passive solutions
Higher power factor than capacitor-fed solutions
Entirely manufacturable in SMD
Table 1. Output Current Table.
Notes:
1. Typical output current in a non-isolated buck converter. Output power
capability depends on respective output voltage. See KeyApplications
Considerations Section for complete description of assumptions,
including fully discontinuous conduction mode (DCM) operation.
2. Mostly discontinuous conduction mode.
3. Continuous conduction mode.
4. Packages: P: DIP-8B, G: SMD-8B, D: SO-8C.
EcoSmart®– Extremely Energy Efficient
•
•
•
Consumes typically only 50/80 mW in self-powered buck
topology at 115/230 VAC input with no load (opto feedback)
Consumes typically only 7/12 mW in flyback topology
with external bias at 115/230 VAC input with no load
Meets California Energy Commission (CEC), Energy
Star, and EU requirements
LinkSwitch-TN devices integrate a 700 V power MOSFET,
oscillator,simpleOn/Offcontrolscheme,ahighvoltageswitched
currentsource, frequencyjittering, cycle-by-cyclecurrentlimit
and thermal shutdown circuitry onto a monolithic IC. The start-
up and operating power are derived directly from the voltage
on the DRAIN pin, eliminating the need for a bias supply and
associated circuitry in buck or flyback converters. The fully
integrated auto-restart circuit in the LNK304-306 safely limits
output power during fault conditions such as short-circuit or
open loop, reducing component count and system-level load
protection cost. A local supply provided by the IC allows use
of a non-safety graded optocoupler acting as a level shifter to
further enhance line and load regulation performance in buck
and buck-boost converters, if required.
Applications
•
•
Appliances and timers
LED drivers and industrial controls
Description
LinkSwitch-TN is specifically designed to replace all linear and
capacitor-fed (cap dropper) non-isolated power supplies in the
under 360 mA output current range at equal system cost while
offering much higher performance and energy efficiency.
November 2008
LNK302/304-306
BYPASS
(BP)
DRAIN
(D)
REGULATOR
5.8 V
BYPASS PIN
UNDER-VOLTAGE
+
-
5.8 V
4.85 V
CURRENT LIMIT
COMPARATOR
6.3 V
+
-
V
ILIMIT
JITTER
CLOCK
DCMAX
THERMAL
SHUTDOWN
OSCILLATOR
FEEDBACK
1.65 V -VT
(FB)
S
R
Q
Q
LEADING
EDGE
BLANKING
SOURCE
(S)
PI-3904-020805
Figure 2a. Functional Block Diagram (LNK302).
DRAIN
(D)
BYPASS
(BP)
REGULATOR
5.8 V
FAULT
PRESENT
AUTO-
RESTART
COUNTER
BYPASS PIN
UNDER-VOLTAGE
+
CLOCK
RESET
5.8 V
4.85 V
-
CURRENT LIMIT
COMPARATOR
6.3 V
+
-
V
ILIMIT
JITTER
CLOCK
DCMAX
THERMAL
SHUTDOWN
OSCILLATOR
FEEDBACK
(FB)
1.65 V -VT
S
R
Q
Q
LEADING
EDGE
BLANKING
SOURCE
(S)
PI-2367-021105
Figure 2b. Functional Block Diagram (LNK304-306).
2
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LNK302/304-306
The LinkSwitch-TN oscillator incorporates circuitry that
introduces a small amount of frequency jitter, typically 4 kHz
peak-to-peak, to minimize EMI emission. The modulation rate
of the frequency jitter is set to 1 kHz to optimize EMI reduction
for both average and quasi-peak emissions. The frequency
jitter should be measured with the oscilloscope triggered at
the falling edge of the DRAIN waveform. The waveform in
Figure 4 illustrates the frequency jitter of the LinkSwitch-TN.
Pin Functional Description
DRAIN (D) Pin:
Power MOSFET drain connection. Provides internal operating
current for both start-up and steady-state operation.
BYPASS (BP) Pin:
Connection point for a 0.1 μF external bypass capacitor for the
internally generated 5.8 V supply.
Feedback Input Circuit
FEEDBACK (FB) Pin:
The feedback input circuit at the FB pin consists of a low
impedancesourcefolloweroutputsetat1.65V.Whenthecurrent
deliveredintothispinexceeds49μA,alowlogiclevel(disable)
is generated at the output of the feedback circuit. This output
is sampled at the beginning of each cycle on the rising edge of
the clock signal. If high, the power MOSFET is turned on for
thatcycle(enabled), otherwisethepowerMOSFETremainsoff
(disabled). Since the sampling is done only at the beginning of
each cycle, subsequent changes in the FB pin voltage or current
during the remainder of the cycle are ignored.
During normal operation, switching of the power MOSFET is
controlled by this pin. MOSFET switching is terminated when
a current greater than 49 μA is delivered into this pin.
SOURCE (S) Pin:
This pin is the power MOSFET source connection. It is also the
ground reference for the BYPASS and FEEDBACK pins.
P Package (DIP-8B)
G Package (SMD-8B)
5.8 V Regulator and 6.3 V Shunt Voltage Clamp
D Package (SO-8C)
The 5.8 V regulator charges the bypass capacitor connected to
the BYPASS pin to 5.8 V by drawing a current from the voltage
on the DRAIN, whenever the MOSFET is off. The BYPASS
pin is the internal supply voltage node for the LinkSwitch-TN.
When the MOSFET is on, the LinkSwitch-TN runs off of the
energy stored in the bypass capacitor. Extremely low power
consumption of the internal circuitry allows the LinkSwitch-TN
tooperatecontinuouslyfromthecurrentdrawnfromtheDRAIN
pin. A bypass capacitor value of 0.1 μF is sufficient for both
high frequency decoupling and energy storage.
S
S
S
S
1
2
8
7
1
2
8
7
BP
FB
S
S
S
S
6
5
BP
FB
3
4
4
D
5
D
3a
3b
PI-3491-120706
In addition, there is a 6.3 V shunt regulator clamping the
BYPASS pin at 6.3 V when current is provided to the BYPASS
pin through an external resistor. This facilitates powering of
LinkSwitch-TN externally through a bias winding to decrease
the no-load consumption to about 50 mW.
Figure 3. Pin Configuration.
LinkSwitch-TN Functional
Description
BYPASS Pin Under-Voltage
LinkSwitch-TNcombinesahighvoltagepowerMOSFETswitch
withapowersupplycontrollerinonedevice.Unlikeconventional
PWM(pulsewidthmodulator)controllers,LinkSwitch-TNuses
a simple ON/OFF control to regulate the output voltage. The
LinkSwitch-TN controller consists of an oscillator, feedback
(sense and logic) circuit, 5.8 V regulator, BYPASS pin under-
voltagecircuit,over-temperatureprotection,frequencyjittering,
current limit circuit, leading edge blanking and a 700 V power
MOSFET.TheLinkSwitch-TNincorporatesadditionalcircuitry
for auto-restart.
The BYPASS pin under-voltage circuitry disables the power
MOSFET when the BYPASS pin voltage drops below 4.85 V.
Once the BYPASS pin voltage drops below 4.85 V, it must rise
back to 5.8 V to enable (turn-on) the power MOSFET.
Over-Temperature Protection
The thermal shutdown circuitry senses the die temperature.
The threshold is set at 142 °C typical with a 75 °C hysteresis.
Whenthedietemperaturerisesabovethisthreshold(142°C)the
power MOSFET is disabled and remains disabled until the die
temperature falls by 75 °C, at which point it is re-enabled.
Oscillator
The typical oscillator frequency is internally set to an average
of 66 kHz. Two signals are generated from the oscillator: the
maximum duty cycle signal (DCMAX) and the clock signal that
indicates the beginning of each cycle.
Current Limit
ThecurrentlimitcircuitsensesthecurrentinthepowerMOSFET.
When this current exceeds the internal threshold (ILIMIT), the
3
Rev. I 11/08
LNK302/304-306
600
500
12 V, 120 mA non-isolated power supply used in appliance
control such as rice cookers, dishwashers or other white goods.
This circuit may also be applicable to other applications such
as night-lights, LED drivers, electricity meters, and residential
heating controllers, where a non-isolated supply is acceptable.
VDRAIN
400
300
The input stage comprises fusible resistor RF1, diodes D3 and
D4, capacitors C4 and C5, and inductor L2. Resistor RF1 is
a flame proof, fusible, wire wound resistor. It accomplishes
several functions: a) Inrush current limitation to safe levels for
rectifiers D3 and D4; b) Differential mode noise attenuation;
c) Input fuse should any other component fail short-circuit
(component fails safely open-circuit without emitting smoke,
fire or incandescent material).
200
100
0
68 kHz
64 kHz
0
20
The power processing stage is formed by the LinkSwitch-TN,
freewheeling diode D1, output choke L1, and the output
capacitor C2. The LNK304 was selected such that the power
supply operates in the mostly discontinuous-mode (MDCM).
Diode D1 is an ultra-fast diode with a reverse recovery time (trr)
of approximately 75 ns, acceptable for MDCM operation. For
continuousconductionmode(CCM)designs,adiodewithatrr of
≤35nsisrecommended. InductorL1isastandardoff-the-shelf
inductor with appropriate RMS current rating (and acceptable
temperature rise). Capacitor C2 is the output filter capacitor;
its primary function is to limit the output voltage ripple. The
output voltage ripple is a stronger function of the ESR of the
output capacitor than the value of the capacitor itself.
Time (μs)
Figure 4. Frequency Jitter.
power MOSFET is turned off for the remainder of that cycle.
The leading edge blanking circuit inhibits the current limit
comparator for a short time (tLEB) after the power MOSFET
is turned on. This leading edge blanking time has been set so
that current spikes caused by capacitance and rectifier reverse
recovery time will not cause premature termination of the
switching pulse.
Auto-Restart (LNK304-306 only)
In the event of a fault condition such as output overload, output
short,oranopenloopcondition,LinkSwitch-TNentersintoauto-
restart operation. An internal counter clocked by the oscillator
gets reset every time the FB pin is pulled high. If the FB pin
is not pulled high for 50 ms, the power MOSFET switching is
disabled for 800 ms. The auto-restart alternately enables and
disables the switching of the power MOSFET until the fault
condition is removed.
To a first order, the forward voltage drops of D1 and D2 are
identical. Therefore, the voltage across C3 tracks the output
voltage.ThevoltagedevelopedacrossC3issensedandregulated
via the resistor divider R1 and R3 connected to U1’s FB pin.
The values of R1 and R3 are selected such that, at the desired
output voltage, the voltage at the FB pin is 1.65 V.
Regulation is maintained by skipping switching cycles. As the
output voltage rises, the current into the FB pin will rise. If
this exceeds IFB then subsequent cycles will be skipped until the
current reduces below IFB. Thus, as the output load is reduced,
more cycles will be skipped and if the load increases, fewer
Applications Example
A 1.44 W Universal Input Buck Converter
The circuit shown in Figure 5 is a typical implementation of a
R1
13.0 kΩ
1%
C3
R3
2.05 kΩ
1%
RF1
10 μF
35 V
D2
1N4005GP
8.2 Ω
L2
C1
FB
BP
S
2 W
1 mH
100 nF
12 V,
120 mA
D
L1
D3
1 mH
LinkSwitch-TN
1N4007
C2
280 mA
85-265
VAC
C4
4.7 μF
400 V
C5
4.7 μF
400 V
R4
3.3 kΩ
LNK304
100 μF
D1
UF4005
16 V
D4
1N4007
RTN
PI-3757-112103
Figure 5. Universal Input, 12 V, 120 mA Constant Voltage Power Supply Using LinkSwitch-TN.
4
Rev. I 11/08
LNK302/304-306
LinkSwitch-TN
RF1
D3
L2
D
FB
BP
S
D2
R1
+
C1
AC
INPUT
S
S
L1
C4
C5
C3
R3
DC
OUTPUT
C2
S
D1
D4
Optimize hatched copper areas (
) for heatsinking and EMI.
PI-3750-121106
Figure 6a. Recommended Printed Circuit Layout for LinkSwitch-TN in a Buck Converter Configuration using P or G Package.
D3
L2
RF1
D
S
S
S
S
L1
+
FB
BP
D1
AC
INPUT
C3
C4
C5
D2
C2
DC
OUTPUT
C1
R3
R1
D4
Optimize hatched copper areas (
) for heatsinking and EMI.
PI-4546-011807
Figure 6b. Recommended Printed Circuit Layout for LinkSwitch-TN in a Buck Converter Configuration using D Package
to Bottom Side of the Board.
cycles are skipped. To provide overload protection if no cycles
are skipped during a 50 ms period, LinkSwitch-TN will enter
auto-restart (LNK304-306), limiting the average output power
to approximately 6% of the maximum overload power. Due to
trackingerrorsbetweentheoutputvoltageandthevoltageacross
C3 at light load or no load, a small pre-load may be required
(R4). For the design in Figure 5, if regulation to zero load is
required, then this value should be reduced to 2.4 kΩ.
1) Buck converter topology.
2) The minimum DC input voltage is ≥70 V. The value of
input capacitance should be large enough to meet this
criterion.
3) For CCM operation a KRP* of 0.4.
4) Output voltage of 12 VDC.
5) Efficiency of 75%.
6) A catch/freewheeling diode with trr ≤75 ns is used for
MDCM operation and for CCM operation, a diode with
trr ≤35 ns is used.
Key Application Considerations
7) The part is board mounted with SOURCE pins soldered
to a sufficient area of copper to keep the SOURCE pin
temperature at or below 100 °C.
LinkSwitch-TN Design Considerations
Output Current Table
*KRP is the ratio of ripple to peak inductor current.
Data sheet maximum output current table (Table 1) represents
the maximum practical continuous output current for both
mostlydiscontinuousconductionmode(MDCM)andcontinuous
conductionmode(CCM)ofoperationthatcanbedeliveredfrom
a given LinkSwitch-TN device under the following assumed
conditions:
LinkSwitch-TN Selection and Selection Between
MDCM and CCM Operation
SelecttheLinkSwitch-TNdevice,freewheelingdiodeandoutput
inductor that gives the lowest overall cost. In general, MDCM
5
Rev. I 11/08
LNK302/304-306
TOPOLOGY BASIC CIRCUIT SCHEMATIC
KEY FEATURES
High-Side
Buck –
Direct
1. Output referenced to input
2. Positive output (VO) with respect to -VIN
3. Step down – VO < VIN
FB
BP
S
Feedback
4. Low cost direct feedback (±10% typ.)
D
+
+
LinkSwitch-TN
VIN
VO
PI-3751-121003
High-Side
Buck –
Optocoupler
Feedback
1. Output referenced to input
2. Positive output (VO) with respect to -VIN
3. Step down – VO < VIN
FB
BP
S
D
+
+
4. Optocoupler feedback
LinkSwitch-TN
- Accuracy only limited by reference
choice
VIN
VO
- Low cost non-safety rated opto
- No pre-load required
5. Minimum no-load consumption
PI-3752-121003
Low-Side
Buck –
+
+
Optocoupler
Feedback
LinkSwitch-TN
VIN
VO
1. Output referenced to input
2. Negative output (VO) with respect to +VIN
3. Step down – VO < VIN
BP
FB
D
S
PI-3753-111903
4. Optocoupler feedback
- Accuracy only limited by reference
choice
Low-Side
Buck –
Constant
Current LED
Driver
+
IO
LinkSwitch-TN
- Low cost non-safety rated opto
- No pre-load required
- Ideal for driving LEDs
VF
VIN
+
BP
FB
D
S
PI-3754-112103
VF
IO
R =
High-Side
Buck Boost –
Direct
FB
BP
S
Feedback
D
+
LinkSwitch-TN
1. Output referenced to input
VIN
VO
+
2. Negative output (VO) with respect to +VIN
3. Step up/down – VO > VIN orVO < VIN
4. Low cost direct feedback (±10% typ.)
5. Fail-safe – output is not subjected to input
voltage if the internal MOSFET fails
6. Ideal for driving LEDs – better accuracy
and temperature stability than Low-side
Buck constant current LED driver
PI-3755-121003
High-Side
Buck Boost –
Constant
Current LED
Driver
2 V
300 Ω
RSENSE
=
IO
2 kΩ
RSENSE
FB
BP
IO
S
D
+
LinkSwitch-TN
VIN
10 μF
50 V
100 nF
PI-3779-120803
Table 2. Common Circuit Configurations Using LinkSwitch-TN. (continued on next page)
6
Rev. I 11/08
LNK302/304-306
KEY FEATURES
TOPOLOGY
BASIC CIRCUIT SCHEMATIC
Low-Side
1. Output referenced to input
2. Positive output (VO) with respect to +VIN
3. Step up/down – VO > VIN or VO < VIN
4. Optocoupler feedback
Buck Boost –
Optocoupler
Feedback
+
LinkSwitch-TN
- Accuracy only limited by reference
choice
VIN
VO
- Low cost non-safety rated opto
- No pre-load required
5. Fail-safe – output is not subjected to input
voltage if the internal MOSFET fails
BP
FB
+
D
S
PI-3756-111903
Table 2 (cont). Common Circuit Configurations Using LinkSwitch-TN.
provides the lowest cost and highest efficiency converter. CCM
designs require a larger inductor and ultra-fast (trr ≤35 ns)
freewheeling diode in all cases. It is lower cost to use a larger
LinkSwitch-TNinMDCMthanasmallerLinkSwitch-TNinCCM
because of the additional external component costs of a CCM
design. However, ifthehighestoutputcurrentisrequired, CCM
should be employed following the guidelines below.
Feedback Diode D2
Diode D2 can be a low-cost slow diode such as the 1N400X
series, however it should be specified as a glass passivated type
to guarantee a specified reverse recovery time. To a first order,
the forward drops of D1 and D2 should match.
Inductor L1
Choose any standard off-the-shelf inductor that meets the
design requirements. A “drum” or “dog bone” “I” core
inductor is recommended with a single ferrite element due to
its low cost and very low audible noise properties. The typical
inductance value and RMS current rating can be obtained from
the LinkSwitch-TN design spreadsheet available within the
PI Expert design suite from Power Integrations. Choose L1
greater than or equal to the typical calculated inductance with
RMS current rating greater than or equal to calculated RMS
inductor current.
Topology Options
LinkSwitch-TN can be used in all common topologies, with or
withoutanoptocouplerandreferencetoimproveoutputvoltage
tolerance and regulation. Table 2 provide a summary of these
configurations. For more information see the Application
Note – LinkSwitch-TN Design Guide.
Component Selection
Referring to Figure 5, the following considerations may be
Capacitor C2
helpful in selecting components for a LinkSwitch-TN design.
The primary function of capacitor C2 is to smooth the inductor
current. The actual output ripple voltage is a function of this
capacitor’s ESR. To a first order, the ESR of this capacitor
shouldnotexceedtheratedripplevoltagedividedbythetypical
current limit of the chosen LinkSwitch-TN.
Freewheeling Diode D1
Diode D1 should be an ultra-fast type. For MDCM, reverse
recovery time trr ≤75 ns should be used at a temperature of
70°Corbelow. Slowerdiodesarenotacceptable,ascontinuous
mode operation will always occur during startup, causing high
leading edge current spikes, terminating the switching cycle
prematurely,andpreventingtheoutputfromreachingregulation.
If the ambient temperature is above 70 °C then a diode with
trr ≤35 ns should be used.
Feedback Resistors R1 and R3
The values of the resistors in the resistor divider formed by
R1 and R3 are selected to maintain 1.65 V at the FB pin. It is
recommended that R3 be chosen as a standard 1% resistor of
2kΩ. Thisensuresgoodnoiseimmunitybybiasingthefeedback
network with a current of approximately 0.8 mA.
For CCM an ultra-fast diode with reverse recovery time
trr ≤35 ns should be used. A slower diode may cause excessive
leading edge current spikes, terminating the switching cycle
prematurely and preventing full power delivery.
Feedback Capacitor C3
Capacitor C3 can be a low cost general purpose capacitor. It
provides a “sample and hold” function, charging to the output
voltage during the off time of LinkSwitch-TN. Its value should
be 10 μF to 22 μF; smaller values cause poorer regulation at
light load conditions.
Fast and slow diodes should never be used as the large reverse
recovery currents can cause excessive power dissipation in the
diode and/or exceed the maximum drain current specification
of LinkSwitch-TN.
7
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LNK302/304-306
Pre-load Resistor R4
Quick Design Checklist
In high-side, direct feedback designs where the minimum load
is <3 mA, a pre-load resistor is required to maintain output
regulation. This ensures sufficient inductor energy to pull the
inductor side of the feedback capacitor C3 to input return via
D2. The value of R4 should be selected to give a minimum
output load of 3 mA.
As with any power supply design, all LinkSwitch-TN designs
should be verified for proper functionality on the bench. The
following minimum tests are recommended:
1) Adequate DC rail voltage – check that the minimum DC
inputvoltagedoesnotfallbelow70VDCatmaximumload,
minimum input voltage.
2) Correct Diode Selection – UF400x series diodes are
recommended only for designs that operate in MDCM at
an ambient of 70 °C or below. For designs operating in
continuousconductionmode(CCM)and/orhigherambients,
then a diode with a reverse recovery time of 35 ns or better,
such as the BYV26C, is recommended.
3) Maximum drain current – verify that the peak drain current
is below the data sheet peak drain specification under
worst-case conditions of highest line voltage, maximum
overload (just prior to auto-restart) and highest ambient
temperature.
4) Thermal check – at maximum output power, minimum
input voltage and maximum ambient temperature, verify
that the LinkSwitch-TN SOURCE pin temperature is
100 °C or below. This figure ensures adequate margin due
to variations in RDS(ON) from part to part. Abattery powered
thermocouplemeterisrecommendedtomakemeasurements
whentheSOURCEpinsareaswitchingnode.Alternatively,
the ambient temperature may be raised to indicate margin
to thermal shutdown.
In designs with an optocoupler the Zener or reference bias
current provides a 1 mA to 2 mA minimum load, preventing
“pulse bunching” and increased output ripple at zero load.
LinkSwitch-TN Layout Considerations
In the buck or buck-boost converter configuration, since the
SOURCEpinsinLinkSwitch-TNareswitchingnodes,thecopper
area connected to SOURCE should be minimized to minimize
EMI within the thermal constraints of the design.
In the boost configuration, since the SOURCE pins are tied
to DC return, the copper area connected to SOURCE can be
maximized to improve heatsinking.
The loop formed between the LinkSwitch-TN, inductor (L1),
freewheeling diode (D1), and output capacitor (C2) should
be kept as small as possible. The BYPASS pin capacitor
C1 (Figure 6) should be located physically close to the
SOURCE (S) and BYPASS (BP) pins. To minimize direct
coupling from switching nodes, the LinkSwitch-TN should be
placed away from AC input lines. It may be advantageous to
place capacitors C4 and C5 in-between LinkSwitch-TN and the
AC input. The second rectifier diode D4 is optional, but may
be included for better EMI performance and higher line surge
withstand capability.
InaLinkSwitch-TNdesignusingabuckorbuckboostconverter
topology, the SOURCE pin is a switching node. Oscilloscope
measurements should therefore be made with probe grounded
to a DC voltage, such as primary return or DC input rail, and
not to the SOURCE pins. The power supply input must always
be supplied from an isolated source (e.g. via an isolation
transformer).
8
Rev. I 11/08
LNK302/304-306
ABSOLUTE MAXIMUM RATINGS(1,5)
DRAIN Voltage ..................................................-0.3Vto700V Notes:
PeakDRAINCurrent(LNK302).................200mA(375 mA)(2) 1. All voltages referenced to SOURCE, TA = 25 °C.
PeakDRAINCurrent(LNK304).................400mA(750 mA)(2) 2. The higher peak DRAIN current is allowed if the DRAIN
PeakDRAINCurrent(LNK305).................800mA(1500 mA)(2)
to SOURCE voltage does not exceed 400 V.
PeakDRAINCurrent(LNK306).................1400mA(2600 mA)(2) 3. Normally limited by internal circuitry.
FEEDBACK Voltage .........................................-0.3 V to 9 V 4. 1/16 in. from case for 5 seconds.
FEEDBACK Current.............................................100 mA 5. Maximum ratings specified may be applied, one at a time,
BYPASS Voltage ..........................................-0.3 V to 9 V
StorageTemperature..........................................-65°C to150°C
OperatingJunctionTemperature(3) .....................-40°C to150°C
Lead Temperature(4) ........................................................260 °C
without causing permanent damage to the product.
Exposure to Absolute Maximum Rating conditions for
extended periods of time may affect product reliability.
THERMAL IMPEDANCE
Thermal Impedance: P or G Package:
Notes:
(θJA) ........................... 70 °C/W(3); 60 °C/W(4) 1. Measured on pin 2 (SOURCE) close to plastic interface.
(θJC)(1) ............................................... 11 °C/W 2. Measured on pin 8 (SOURCE) close to plastic interface.
D Package:
3. Soldered to 0.36 sq. in. (232 mm2), 2 oz. (610 g/m2) copper clad.
(θJA) ..................... .... 100 °C/W(3); 80 °C/W(4) 4. Soldered to 1 sq. in. (645 mm2), 2 oz. (610 g/m2) copper clad.
(θJC)(2) ............................................... 30 °C/W
Conditions
SOURCE = 0 V; TJ = -40 to 125 °C
Parameter
Symbol
Min
Typ
Max
Units
See Figure 7
(Unless Otherwise Specified)
CONTROL FUNCTIONS
Average
TJ = 25 °C
62
66
4
70
Output
fOSC
kHz
%
Frequency
Peak-Peak Jitter
Maximum Duty
DCMAX
Cycle
S2 Open
66
30
69
49
72
68
FEEDBACK Pin
IFB
TJ = 25 °C
μA
Turnoff Threshold
Current
FEEDBACK Pin
Voltage at Turnoff
Threshold
VFB
1.54
1.65
160
1.76
220
V
VFB ≥2 V
(MOSFET Not Switching)
See Note A
IS1
μA
DRAIN Supply
Current
FEEDBACK
Open
(MOSFET
Switching)
See Notes A, B
LNK302/304
LNK305
200
220
250
260
280
310
IS2
μA
LNK306
9
Rev. I 11/08
LNK302/304-306
Conditions
SOURCE = 0 V; TJ = -40 to 125 °C
See Figure 7
Parameter
Symbol
Min
Typ
Max
Units
(Unless Otherwise Specified)
CONTROL FUNCTIONS (cont.)
LNK302/304
LNK305/306
LNK302/304
LNK305/306
-5.5
-7.5
-3.8
-4.5
-3.3
-4.6
-2.3
-3.3
-1.8
-2.5
-1.0
-1.5
VBP = 0 V
TJ = 25 °C
ICH1
BYPASS Pin
Charge Current
mA
VBP = 4 V
TJ = 25 °C
ICH2
BYPASS Pin
VBP
5.55
0.8
68
5.8
6.10
1.2
V
V
Voltage
BYPASS Pin
VBPH
Voltage Hysteresis
0.95
BYPASS Pin
IBPSC
Supply Current
See Note D
μA
CIRCUIT PROTECTION
di/dt = 55 mA/μs
TJ = 25 °C
126
145
240
271
350
396
450
136
165
257
308
375
450
482
146
185
275
345
401
504
515
LNK302
LNK304
LNK305
di/dt = 250 mA/μs
TJ = 25 °C
di/dt = 65 mA/μs
TJ = 25 °C
di/dt = 415 mA/μs
TJ = 25 °C
ILIMIT (See
Note E)
mA
Current Limit
di/dt = 75 mA/μs
TJ = 25 °C
di/dt = 500 mA/μs
TJ = 25 °C
di/dt = 95 mA/μs
TJ = 25 °C
LNK306
di/dt = 610 mA/μs
TJ = 25 °C
508
280
578
360
647
475
LNK302/304
tON(MIN)
ns
Minimum On Time
LNK305
LNK306
360
400
460
500
610
675
Leading Edge
Blanking Time
TJ = 25 °C
See Note F
tLEB
170
135
215
142
ns
°C
Thermal Shutdown
Temperature
TSD
150
10
Rev. I 11/08
LNK302/304-306
Conditions
SOURCE = 0 V; TJ = -40 to 125 °C
See Figure 7
Parameter
Symbol
Min
Typ
Max
Units
(Unless Otherwise Specified)
CIRCUIT PROTECTION (cont.)
Thermal Shutdown
TSHD
Hysteresis
See Note G
75
°C
OUTPUT
TJ = 25 °C
48
76
24
38
12
19
7
55.2
88.4
27.6
44.2
13.8
22.1
8.1
LNK302
ID = 13 mA
TJ = 100 °C
TJ = 25 °C
LNK304
ID = 25 mA
TJ = 100 °C
ON-State
RDS(ON)
Resistance
Ω
TJ = 25 °C
TJ = 100 °C
TJ = 25 °C
TJ = 100 °C
LNK302/304
LNK305
LNK305
ID = 35 mA
LNK306
ID = 45 mA
11
12.9
50
VBP = 6.2 V, VFB ≥2 V,
VDS = 560 V,
OFF-State Drain
Leakage Current
70
IDSS
μA
TJ = 25 °C
LNK306
90
VBP = 6.2 V, VFB ≥2 V,
TJ = 25 °C
BVDSS
700
50
V
Breakdown Voltage
tR
tF
50
50
ns
ns
Rise Time
Fall Time
Measured in a Typical Buck
Converter Application
DRAIN Supply
Voltage
V
μs
μs
ms
%
Output Enable
Delay
tEN
See Figure 9
10
Output Disable
Setup Time
tDST
0.5
Not Applicable
LNK302
Auto-Restart
ON-Time
TJ = 25 °C
See Note H
tAR
LNK304-306
50
Not Applicable
LNK302
Auto-Restart
Duty Cycle
DCAR
LNK304-306
6
11
Rev. I 11/08
LNK302/304-306
NOTES:
A. Total current consumption is the sum of IS1 and IDSS when FEEDBACK pin voltage is ≥2 V (MOSFET not
switching) and the sum of IS2 and IDSS when FEEDBACK pin is shorted to SOURCE (MOSFET switching).
B Since the output MOSFET is switching, it is difficult to isolate the switching current from the supply current at the
DRAIN. An alternative is to measure the BYPASS pin current at 6 V.
C. See Typical Performance Characteristics section Figure 14 for BYPASS pin start-up charging waveform.
D. This current is only intended to supply an optional optocoupler connected between the BYPASS and FEEDBACK
pins and not any other external circuitry.
E. For current limit at other di/dt values, refer to Figure 13.
F. This parameter is guaranteed by design.
G. This parameter is derived from characterization.
H. Auto-restart on time has the same temperature characteristics as the oscillator (inversely proportional to
frequency).
470 Ω
5 W
470 kΩ
0.1 μF
FB
BP
D
S2
S1
50 V
50 V
S
S
S
S
PI-3490-060204
Figure 7. LinkSwitch-TN General Test Circuit.
DC
(internal signal)
MAX
t
P
FB
t
EN
V
DRAIN
1
tP
=
fOSC
PI-3707-112503
Figure 9. LinkSwitch-TN Output Enable Timing.
Figure 8. LinkSwitch-TN Duty Cycle Measurement.
12
Rev. I 11/08
LNK302/304-306
Typical Performance Characteristics
1.2
1.0
0.8
0.6
0.4
0.2
1.1
1.0
0.9
0
-50 -25
0
25 50 75 100 125 150
-50 -25
0
25
50 75 100 125
Junction Temperature (°C)
Junction Temperature (°C)
Figure 10. Breakdown vs. Temperature.
Figure 11. Frequency vs. Temperature.
1.4
1.2
1.0
0.8
1.4
1.2
1.0
0.8
Normalized
Normalized Current
Normalized di/dt
di/dt = 1
di/dt = 6
0.6
0.4
0.2
0
0.6
0.4
0.2
0
di/dt = 1
Limit = 1
LNK302
LNK304
LNK305
LNK306
55 mA/μs
65 mA/μs
75 mA/μs
95 mA/μs
136 mA
257 mA
375 mA
482 mA
1
2
3
4
5
6
-50
0
50
100
150
Normalized di/dt
Temperature (°C)
Figure 13. Current Limit vs. di/dt.
Figure 12. Current Limit vs. Temperature at
Normalized di/dt.
7
6
5
400
350
25 °C
300
100 °C
250
200
150
100
50
4
3
2
1
Scaling Factors:
LNK302 0.5
LNK304 1.0
LNK305 2.0
LNK306 3.4
0
0
0
0.2
0.4
Time (ms)
Figure 14. BYPASS Pin Start-up Waveform.
0.6
0.8
1.0
0
2
4
6
8
10 12 14 16 18 20
DRAIN Voltage (V)
Figure 15. Output Characteristics.
13
Rev. I 11/08
LNK302/304-306
Typical Performance Characteristics (cont.)
1000
100
Scaling Factors:
LNK302
LNK304
LNK305
LNK306
0.5
1.0
2.0
3.4
10
1
0
100 200 300 400 500 600
Drain Voltage (V)
Figure 16. COSS vs. Drain Voltage.
PART ORDERING INFORMATION
LinkSwitch Product Family
TN Series Number
Package Identifier
G
P
D
Plastic Surface Mount DIP
Plastic DIP
Plastic SO-8C
Lead Finish
N
G
Pure Matte Tin (RoHS Compliant)
RoHS Compliant and Halogen Free (D package only)
Tape & Reel and Other Options
Blank Standard Configurations
Tape & Reel, 1 k pcs minimum for G Package. 2.5 k pcs
for D Package. Not available for P Package.
TL
LNK 304 G N - TL
14
Rev. I 11/08
LNK302/304-306
DIP-8B
⊕
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-
.367 (9.32)
.387 (9.83)
7. Lead spacing measured with the leads constrained to be
perpendicular to plane T.
.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)
.300 (7.62)
.390 (9.91)
.100 (2.54) BSC
.048 (1.22)
.053 (1.35)
P08B
.014 (.36)
.022 (.56)
⊕
T E D S .010 (.25) M
PI-2551-121504
SMD-8B
⊕
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
Pin 1
-D-
.086
.186
.100 (2.54) (BSC)
5. Lead width measured at
package body.
6. D and E are referenced
datums on the package
body.
.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-2546-121504
15
Rev. I 11/08
LNK302/304-306
SO-8C
0.10 (0.004)
A-B
2X
C
2
DETAIL A
B
4
4.90 (0.193) BSC
A
4
D
8
5
GAUGE
PLANE
SEATING
PLANE
3.90 (0.154) BSC
6.00 (0.236) BSC
2
0 - 8o
C
0.25 (0.010)
BSC
1.04 (0.041) REF
0.10 (0.004)
C D
0.40 (0.016)
1.27 (0.050)
2X
1
4
Pin 1 ID
0.20 (0.008) C
2X
7X 0.31 - 0.51 (0.012 - 0.020)
0.25 (0.010)
1.27 (0.050) BSC
M
C A-B D
1.25 - 1.65
(0.049 - 0.065)
1.35 (0.053)
1.75 (0.069)
DETAIL A
H
0.10 (0.004)
0.25 (0.010)
0.10 (0.004)
C
7X
SEATING PLANE
0.17 (0.007)
0.25 (0.010)
C
Reference
Solder Pad
Dimensions
+
Notes:
1. JEDEC reference: MS-012.
2. Package outline exclusive of mold flash and metal burr.
3. Package outline inclusive of plating thickness.
4. Datums A and B to be determined at datum plane H.
2.00 (0.079)
4.90 (0.193)
5. Controlling dimensions are in millimeters. Inch dimensions
are shown in parenthesis. Angles in degrees.
+
+
+
1.27 (0.050)
0.60 (0.024)
D07C
PI-4526-040207
16
Rev. I 11/08
LNK302/304-306
Notes
17
Rev. I 11/08
LNK302/304-306
Notes
18
Rev. I 11/08
LNK302/304-306
Revision Notes
Date
3/03
1/04
8/04
12/04
3/05
C
D
E
F
1) Released final data sheet.
1) Corrected Minimum On Time.
1) Added LNK302.
1) Added lead-free ordering information.
G
1) Minor error corrections.
2) Renamed Feedback Pin Voltage parameter to Feedback Pin Voltage at Turnoff Threshold and
removed condition.
H
I
1) Added SO-8C package.
12/06
11/08
1) Updated Part Ordering Information section with Halogen Free
19
Rev. I 11/08
LNK302/304-306
For the latest updates, visit our website: 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. 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.powerint.com. Power Integrations grants its customers a license under
certain patent rights as set forth at http://www.powerint.com/ip.htm.
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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, DPA-Switch, PeakSwitch, EcoSmart, Clampless, E-Shield, Filterfuse, StakFET, PI Expert
and PI FACTS are trademarks of Power Integrations, Inc. Other trademarks are property of their respective companies.
©2006, Power Integrations, Inc.
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20
Rev. I 11/08
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