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Energy Saving Products
101 N.Sepulveda Blvd, EL Segundo 90245 California, USA
IRAC27951SR
IRS27951 Evaluation Board
User Guide
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Table of Contents
1 INTRODUCTION ........................................................................................................................ 3
2 IRS27951/2 DESCRIPTION ....................................................................................................... 3
3 IR11682 DESCRIPTION ............................................................................................................ 4
4 EVALUATION BOARD SPECIFICATIONS ................................................................................ 5
4.1 Board Description ................................................................................................................... 5
4.2 Schematic ............................................................................................................................... 6
4.3 Evaluation Board Picture ........................................................................................................ 7
4.4 Board Component Placement ................................................................................................. 7
4.5 Board PCB Layout .................................................................................................................. 8
4.6 Bill of Materials ....................................................................................................................... 9
5 EVALUATION BOARD OPERATING PROCEDURE ............................................................... 10
5.1 Load Connection................................................................................................................... 10
5.2 AC/DC Input ......................................................................................................................... 10
5.3 IRS27951 DC Supply Voltage .............................................................................................. 11
5.4 Disconnect the Board ........................................................................................................... 11
6 SYSTEM PERFORMANCE CHARACTERIZATION ................................................................ 12
6.1 Steady-State and Start-up Waveforms ................................................................................. 12
6.2 Synchronous Rectifier Waveform ......................................................................................... 15
6.3 Dynamic Load Response & Output Voltage Regulation ....................................................... 16
6.4 Output Ripple ........................................................................................................................ 19
6.5 User Initiated SLEEP Mode .................................................................................................. 20
6.6 Efficiency Chart..................................................................................................................... 21
6.7 Thermal Data ........................................................................................................................ 22
7 Transformer Spec..................................................................................................................... 22
7.1 Electrical Diagram ................................................................................................................. 22
7.2 Resonant Transformer Winding Position on Coil former ....................................................... 23
7.3 Resonant Transformer Winding Characteristics ................................................................... 23
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1 INTRODUCTION
This document details the test procedure for validation of IRAC27951SR-240W Evaluation Board,
featuring the IRS27951 Resonant Half Bridge controller and the IR11682 dual-channel synchronous
rectification controller. The document includes schematic diagram, test setup, test procedure, and test
results.
2 IRS27951/2 DESCRIPTION
The IRS2795(1,2) is an 8 pin, high-voltage, double-ended controller specific for the resonant half-bridge
topology. It provides 50% complementary duty cycle; the high-side and the low-side devices are driven 180°
out-of-phase for exactly the same time. The IC incorporates additional protection features for robust operation
and provides a high performance solution while minimizing external components and printed circuit board area.
The IC enables the designer to externally program all the following features using a 2 pin oscillator - operating
frequency range (minimum and maximum frequency), startup frequency, dead time, soft-start time and sleep
mode. Each of these functions are programmed as follows –
The minimum frequency is programmed using RT and CT.
The dead time is programmed using CT.
RSS and CSS program the converter soft-start time.
RSS//RT and CT program the converter start-up frequency.
The converter maximum frequency is set by (Rmax//RT) and CT.
Sleep mode is initiated by pulling the CT/SD to COM.
At start-up, to prevent uncontrolled inrush current, the switching frequency starts from a programmable
maximum value and progressively decays until it reaches the steady-state value determined by the control
loop. This frequency shift is non linear to minimize output voltage overshoot and its duration is programmable
as well. Output voltage regulation is obtained by modulating the operating frequency. An externally
programmable dead time is inserted between the turn-OFF of one switch and the turn-ON of the other one
allows device zero-voltage turn-on transitions.
IRS2795 uses IR’s proprietary high-voltage technology to implement a VS sensing circuitry that monitors the
current through the low-side half bridge MOSFET for short circuit faults. By using the R
DSON
of the low-side
MOSFET, the IRS2795 eliminates the need for an additional current sensing resistor, filter and current-sensing
pin. This protection feature is latched and the thresholds are fixed at 2V for IRS27951 and 3V for IRS27952.
Finally, the controller IC also features a micro power startup current (I
CC
<100µA) and a user initiated sleep
mode during which the IC power consumption is less than 200µA (@ Vcc=15V). The sleep mode function
allows system designs with reduced standby power consumption and can be used to meet stringent energy
standards from Blue Angel, Energy Star etc.
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3 IR11682 DESCRIPTION
IR11682 is a secondary-side SmartRectifier
TM
driver IC designed to drive two N-Channel power MOSFETs
used as synchronous rectifiers in resonant converter applications. The IC can control one or more paralleled N
MOSFETs to emulate the behavior of Schottky diode rectifiers. The drain to source for each rectifier MOSFET
voltage is sensed differentially to determine the level of the current and the power switch is turned ON and
OFF in close proximity of the zero current transition.
When the conduction phase of the SR FET is initiated, current will start flowing through its body diode,
generating a negative VDS voltage across it. The body diode has generally a much higher voltage drop than
the one caused by the MOSFET on resistance and therefore will trigger the turn-on threshold V
TH2
. When V
TH2
is triggered, IR11682 will drive the gate of MOSFET on which will in turn cause the conduction voltage VDS to
drop down to ID*RDSON. This drop is usually accompanied by some amount of ringing, that could trigger the
input comparator to turn off; hence, a fixed Minimum On Time (MOT) blanking period is used that will maintain
the power MOSFET on for a minimum amount of time.
Once the SR MOSFET has been turned on, it will remain on until the rectified current will decay to the level
where VDS will cross the turn-off threshold V
TH1
. Once the threshold is crossed, the current will start flowing
again through the body diode, causing the VDS voltage to jump negative. Hence, V
TH2
is blanked for a time
duration t
BLANK
after V
TH1
is triggered. When the device VDS crosses the positive reset threshold V
TH3
, t
BLANK
is
terminated and the IC is ready for next conduction cycle as shown below.
Gate Drive
VDS
Blanking
time
T1 T2
VTH1
VTH2
VTH3
MOT tBLANK
IDS
IR11682 further simplifies synchronous rectifier control by offering the following power management features:
- Wide VCC operating range allows the IC to be directly powered from the converter output
- Shoot through protection logic that prevents both the GATE outputs from the IC to be high at the same time
- Device turn ON and OFF in close proximity of the zero current transition with low turn-on and turn-off
propagation delays; eliminates reactive power flow between the output capacitors and power transformer
- Cycle-by-cycle MOT protection circuit can automatically detect no load condition and turn off gate driver
output to avoid negative current flowing through the MOSFETs
- Internally clamped gate driver outputs that significantly reduce gate losses
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4 EVALUATION BOARD1 SPECIFICATIONS
Input Voltage...……….……………………………………………………………….280VAC or 400VDC
AC Line Frequency Range…………………………………………………………..47 – 63Hz
Converter Switching Frequency Range…………………………………………….70-150 kHz
Converter Output....…………………………………………………………………..24V/10A
Maximum Output Power…………………………………………………………......240W
Minimum Load Requirement…………………………………………………………None
Maximum Ambient Operating Temperature………………………………………..40°C
2
Efficiency (@ 240W)……...…………………………………………….……….……. 95%
Short Circuit Protection………………………....……………………………………. Yes
Double Layer PCB with 2oz Copper
There are high voltages present whenever the board is energized and proper precautions should be
taken to avoid potential shock and personal injury.
4.1 Board Description
The evaluation board consists of a front-end AC-DC rectifier stage cascaded with a half-bridge resonant DC-
DC converter with 24V output voltage rail.
The front end is a conventional rectifier stage with a rectifier bridge and an EMI filter.
The downstream converter is a multi-resonant half bridge LLC converter whose control is implemented with the
IRS27951 (U1) controller HVIC. The controller drives the two half-bridge MOSFETs with a 50 percent fixed
duty cycle with dead-time, changing the frequency according to the feedback signal in order to regulate the
output voltage against load and input voltage variations. As described earlier, in addition to current protection,
all the critical functions needed to control resonant converter designs can be externally programmed using this
8 pin controller IC.
IRS27951 is self-supplied in this reference design. The startup resistors Rstart1~Rstart3 provide startup
current to IRS27951 during power up and charge the Vcc capacitors (CDC2 and CVcc1). Once Vcc voltage
exceeds Vccuv+ threshold, IRS27951 starts operation and the auxiliary winding of power transformer can
1
Please note that EMI measurements have not been performed on this evaluation board. The primary goal of this board is to verify the functionality of
the IRS27951 controller IC.
2
A fan is recommended whenever operating at the maximum load for a prolonged period of time.
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provide bias to the IC. The voltage of auxiliary winding could vary a lot when 24V load changes from 0A to
10A, so a linear regulator – Dz4, Rvcc and Q2 – is used to keep Vcc regulated at 14.5V.
The transformer uses the magnetic integration approach, incorporating the resonant series and shunt
inductances in the power transformer. The transformer configuration chosen for the secondary winding is
center-tap. The feedback loop is implemented by means of a classical configuration using a TL431 (U3) to
adjust the current in the optocoupler TLP621 (U2). The optocoupler transistor modulates the current from the
RT pin of the controller IC to modulate the switching frequency, thus achieving output voltage regulation.
The secondary rectification is implemented with synchronous rectification controller IR11682 and two PQFN
power MOSFETs. Each leg of the output uses one IRFH5006, a 60V MOSFET with 3.5mohm on state
resistance (typical). The conduction power loss is greatly reduced by using synchronous rectification. No
heatshink is required for 10A continuous output current. PCB area is also saved with the highly integrated dual-
channel SmartRectifier
TM
controller IR11682.
The synchronous rectification circuit is connected in a low-side configuration. So IR11682 can directly drive the
two SR MOSFETs. A RCD circuit is added to IR11682 VD sensing input to provide leading edge filter and turn-
off delay compensation.
IR11682 is biased by 24V output through a simple linear voltage regulator Q1 (a general NPN transistor) and
zener Dz2 (12V). In addition, a second zener diode Dz3 (9.1V) is used to prevent the synchronous rectifier
circuit be activated when output voltage is still low. The IR11682 will start operation when output voltage is
approaching 18V.
4.2 Schematic
Figure 1 – Evaluation Board Schematic
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4.3 Evaluation Board Picture
Figure 2 – Evaluation Board Photo
4.4 Board Component Placement
Figure 3 – Evaluation Board Top Side Component Placement
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Figure 4 – Evaluation Board Bottom Side Component Placement
4.5 Board PCB Layout
Figure 5 - Board Top Layer Copper
Figure 6 - Board Bottom Layer Copper
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4.6 Bill of Materials
Designator Description Quantity Value/Rating Vendor Part#
24V, COMP, CT_, FB, Gate1,
Gate2, HO, LO, RT_, Vcc,
VD1, VD2, VS, VTR Test Point PC Mini 0.040''D 14 Red DIGIKEY 5000K-ND
B1 Single Phase Bridge Rectifier 1 GBU4J-BPMS-ND DIGIKEY GBU4J-BPMS-ND
C1, C2 X2 Safety Capacitor 2 0.1uF/275V-X2 DIGIKEY P10730-ND
C3 Metal Poly Capacitor 1 0.22uF/630V DIGIKEY P12173-ND
C4 Electrolytic Bulk Capacitor TS-HC 1 270uF/450V DIGIKEY P14116-ND
C5 250VAC Y1 Safety Ceramic Disc Capacitor 1 2.2nF/250V DIGIKEY 445-2411-ND
Cbs 1206 General Purpose Ceramic SMD 1 220nF DIGIKEY 490-1776-1-ND
CD1, CD2 0805 General Purpose Ceramic SMD 2 470pF DIGIKEY 311-1119-1-ND
CDC, CDC2 Electrolytic Capacitor FM Radial 2 33uF/35V DIGIKEY 565-1687-ND
Cf1 1206 General Purpose Ceramic SMD 1 220pF/50V DIGIKEY 478-1484-1-ND
Cf2, Cout5 1206 General Purpose Ceramic SMD 2 100nF DIGIKEY 490-1775-1-ND
Cf3 1206 General Purpose Ceramic SMD 1 4.7nF DIGIKEY 490-3357-6-ND
COM, COM2 Test Point PC Mini 0.040''D 2 Black DIGIKEY 5001K-ND
CON1 CONN HEADER 3POS 0.156 VERT TIN 1 AC IN DIGIKEY WM4621-ND
CON3 CONN HEADER 6POS 0.156 VERT TIN 1 Header 6 DIGIKEY WM4624-ND
Cout1, Cout2, Cout3, Cout4 Aluminium Electrolytic Capacitor FM RAD 4 1000uF/35V DIGIKEY P12405-ND
Cr Polypropylene Capacitor High Ripple 1 22nF/400V AC DIGIKEY 495-1329-ND
CSS, CVcc1 1206 General Purpose Ceramic SMD 2 1uF/25V DIGIKEY 445-1592-1-ND
CT 1206 General Purpose Ceramic SMD 1 390pF DIGIKEY 478-1487-1-ND
CVcc3, CDC3 1210 General Purpose Ceramic SMD 2 10uF/25V DIGIKEY 445-3942-1-ND
D1, D2, D5, Dg1, Dg2, DSS Fast Recovery Diode SMD 6 1N4148 DIGIKEY 1N4148W-FDICT-ND
Dbs Fast Recttifier diode SMB 1 MURS160 DIGIKEY MURS160-FDICT-ND
Dz1 Zener Diode SOD80 1 18V DIGIKEY FLZ18VCCT-ND
Dz2 Zener Diode SOD80 1 12V DIGIKEY FLZ12VCCT-ND
Dz3 Zener Diode SOD80 1 9.1V DIGIKEY FLZ9V1CCT-ND
Dz4 Zener Diode SOD80 1 15V DIGIKEY FLZ15VCCT-ND
F1 FUSE IEC FA LBC 5x20 1 5A/250V DIGIKEY F2395-ND
L1 EMI Common Mode Choke 1 Trans Cupl COILCRAFT CMT2-6.5-2L
Lf1 PCV Series Drum Core Inductor 1 1uH/10A COILCRAFT PCV-0-102-10L
M1, M2 TO-220 N-Channel Power MOSFET 2 STF18NM60N DIGIKEY STF18NM60N
M3, M4 N-Channel MOSFET 60V PQFN 2 IRFH5006 INTERNATIONAL RECTIFIER IRFH5006
Q1, Q2 NPN General Purpose Amplifier 2 2N3904 DIGIKEY 2N3904-APCT-ND
Rbias1, Rf3 1206 SMD Film RED 1/4W 5% 2 2k DIGIKEY RHM2.00kFCT-ND
Rcc1 1206 SMD Film RED 1/4W 5% 1 100 DIGIKEY RHM100FCT-ND
Rcc2, Rvcc 1206 SMD Film RED 1/4W 5% 2 2.2K DIGIKEY RHM2.20KFCT-ND
RD1, RD2 0805 SMD Film RED 1/4W 5% 2 1.5K DIGIKEY RHM1.50KCCT-ND
RD3, RD4 0805 SMD Film RED 1/4W 5% 2 100 DIGIKEY RHM100CCT-ND
RDC 1206 SMD Film RED 1/4W 5% 1 200 DIGIKEY RHM200FCT-ND
Rf2 1206 SMD Film RED 1/4W 5% 2 12k DIGIKEY RHM12.0kFCT-ND
Rg1, Rg2, Rvcc1 1206 SMD Film RED 1/4W 5% 3 22 DIGIKEY RHM22.0FCT-ND
RgM3, RgM4 1206 SMD Film RED 1/4W 5% 2 1 DIGIKEY RHM1.00FCT-ND
Rgs1, Rgs2 1206 General Purpose SMD 2 DNP DIGIKEY NOT USED
RL Resistor 1W 5% 1 1K DIGIKEY RSF100JB-1K0
RL1 1210 Resistor 0.5W 5% 1 3K DIGIKEY 541-3.0KVCT-ND
Rled1 1206 SMD Film RED 1/4W 1% 1 5.6k DIGIKEY RHM5.60KFCT-ND
RMAX 1206 SMD Film RED 1/4W 1% 1 14.7k DIGIKEY RHM14.7kFCT-ND
RNTC Inrush Current Limiter 1 5 DIGIKEY 495-2093-ND
Rs1 1206 SMD Film RED 1/4W 1% 1 33k DIGIKEY RHM33.0KFCT-ND
Rs2 1206 SMD Film RED 1/4W 1% 1 680 DIGIKEY RHM680FCT-ND
Rs3 1206 SMD Film RED 1/4W 1% 1 3.9k DIGIKEY RHM3.90KFCT-ND
RSS 1206 SMD Film RED 1/4W 1% 1 8.2k DIGIKEY RHM8.20KFCT-ND
Rstart1, Rstart2, Rstart3 1206 SMD Film RED 1/4W 5% 3 270K DIGIKEY RHM270KFCT-ND
RT 1206 SMD Film RED 1/4W 1% 1 20k DIGIKEY RHM20.0KFCT-ND
Rx1, Rx2 1206 SMD Film RED 1/4W 5% 2 4.7 DIGIKEY 311-4.70FRCT-ND
TX Resonant Power Transformer 1 TRANSYJ YUJING LP3925H
U1 IRS27951 Control IC 1 IRS27951 INTERNATIONAL RECTIFIER IRS27951
U2 Photocoupler TRANS-OUT 4-DIP 1 TLP621 DIGIKEY TLP621FT-ND
U3 Programmable Voltage Regulator SOT23-3 1 TL431 DIGIKEY 568-4883-1-ND
U4 Sync Rect Controller 1 IR11682 INTERNATIONAL RECTIFIER IR11682S
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5 EVALUATION BOARD OPERATING PROCEDURE
CAUTION: Potentially lethal voltages exist on this demo board when powered up. Improper
or unsafe handling of this board may result in serious injury or death.
5.1 Load Connection
Connect a resistive or electronic load, capable of 240W continuous power on the 24V rail to connector CON3.
Please note that there is no minimum load
3
requirement for this board.
5.2 AC/DC Input
The evaluation board can take either AC or DC input voltage. If an AC source is used, an isolation transformer
on the AC side is highly recommended, so that all the control signals on the test points can easily be probed by
using regular scope probes. Connect an AC power source capable of operation up to 280VAC or a 400V DC
source to CON1. The converter can keep the output regulated when the BUS voltage is in the range of 350V
DC to 420V DC.
The NTC resistor limits the inrush current upon initial application of full AC line voltage. Once power is applied
to demo board, potentially lethal high voltages will be present on board and necessary precautions should be
taken to avoid serious injury.
3
A dummy load has been added to the output rail to ensure tight voltage regulation from no load to full load.
Figure 7 - Recommended Evaluation Board Test Setup
ISOLATION
TRANSFORMER
Variable AC
or HV DC
Source
(Variac or
Electronic)
Electronic or
Resistive
Load
24V/10A
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5.3 IRS27951 DC Supply Voltage
The board is self-supplied by startup circuit and auxiliary winding of transformer. The startup circuit starts to
work once AC or DC input voltage applies to the board. However, the Vcc will be stable only when BUS
voltage is 350Vdc or above. The VCC voltage is monitored at test points VCC and COM.
5.4 Disconnect the Board
It is recommended to discharge the bulk capacitor C4 every time after evaluation is finished:
- Disconnect the high voltage AC or DC source from CON1
- Apply an external 12V DC voltage to primary Vcc and COM test points for a while until bus voltage
drops to 0V
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6 SYSTEM PERFORMANCE CHARACTERIZATION
6.1 Steady-State and Start-up Waveforms
Test Conditions – V
IN
= 350V DC; Full Load (24V/10A); No Load (24V/0A)
Ch 1: Low-side device V
GS
– Ch 2: Voltage at VS pin
Ch 4: Resonant tank current
Full Load Operation No Load Operation
Ch 2: Output Voltage Ch 4: Resonant tank current
Full Load Start-up No Load Start-up
At startup, synchronous rectifier circuit activates when Vout voltage is around 18V. As the voltage drop of SR MOSFET is
0.6V lower than body diode forward voltage drop, the output voltage has a small step-up. It also causes primary current a
small peaking due to the charging current of output capacitor.
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Test Conditions – V
IN
= 390V DC; Full Load (24V/10A); No Load (24V/0A)
Ch 1: Low-side device V
GS
– Ch 2: Voltage at VS pin
Ch 4: Resonant tank current
Full Load Operation No Load Operation
Ch 2: Output Voltage Ch 4: Resonant tank current
Full Load Start-up No Load Start-up
The switching frequency sweeps from 200khz to regulation frequency in 10ms~15ms, prevents high current spike during
startup. The output voltage has no overshoot during startup.
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Test Conditions – V
IN
= 420V DC; Full Load (24V/10A); No Load (24V/0A)
Ch 1: Low-side device V
GS
– Ch 2: Voltage at VS pin
Ch 4: Resonant tank current
Full Load Operation No Load Operation
Ch 2: Output Voltage Ch 4: Resonant tank current
Full Load Start-up No Load Start-up
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6.2 Synchronous Rectifier Waveform
Ch 1: SR gate1 – Ch 2: SR gate2
Ch 2: Voltage at VS pin – Ch 4: Resonant tank current
350Vdc, No Load Operation 350Vdc, Full Load Operation
385Vdc, Full Load Operation 420Vdc, Full Load Operation
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6.3 Dynamic Load Response & Output Voltage Regulation
A load step from full load to no load and from no load to full load was applied to test the dynamic response of
the system. The undershoot and overshoot are within +/-3%.
Ch2 : 24V Rail output voltage Ch 4: Resonant tank current
Load Step at 350Vdc input
No Load to Full Load Step at 350Vdc Full Load to No Load Step at 350Vdc
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Load Step at 390Vdc input
No Load to Full Load Step at 390Vdc Full Load to No Load Step at 390Vdc
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Load Step at 420Vdc input
No Load to Full Load Step at 420Vdc Full Load to No Load Step at 420Vdc
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The output voltage is tightly regulated within a +/-1% regulation band over the entire line load range. A
summary of the load performance is also shown below.
Load Regulation
23.00
23.10
23.20
23.30
23.40
23.50
23.60
23.70
23.80
23.90
24.00
0.00 2.00 4.00 6.00 8.00 10.00
Iout (A)
Vout (V)
350 VDC Input
390 VDC Input
420 VDC Input
Figure 8 - Output voltage regulation plot
6.4 Output Ripple
The 24V output ripple is very tiny under DC input voltage. It is bigger with AC input. Below is the 24V ripple
waveform tested at 270Vac and 10A full load.
The ripple is mainly due to the low frequency (2xfAC ) ripple on primary bus voltage. It will be much smaller if
use a PFC pre-regulator in the front stage.
At light load, the Sync Rect circuit could go into standby mode if output current is too small. The gate of
IR11682 will be disabled and the body diode of SR MOSFET will carry output current. Depends on the load
condition, IR11682 may have burst output as shown in the waveform. There will be some output ripple due to
the burst operation of Sync Rect. The ripple is within 200mV and less than 1% of the rated output.
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IR11682 in burst mode at 390Vdc, no load.
Ch1 is the gate1 of IR11682
6.5 User Initiated SLEEP Mode
The CT/SD pin of IRS27951 can be used to disable the IC and enter sleep mode in which the IC power
consumption is highly minimized. The IC enters this mode when the CT/SD pin is externally pulled to COM.
This feature facilitates the implementation of system power management functions for reducing overall standby
power consumption by disabling the down converter when no power is being requested by the converter main
output voltage rails.
Ch 1: Low-side device V
GS
Ch 2: CT/SD pin of IRS27951
Ch 3: High-side device V
GS
Ch 4: Resonant tank current
Sleep mode initiated by externally pulling the CT/SD pin to COM
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6.6 Efficiency Chart
The efficiency of IRS27951 demo board was tested at 350V, 390V and 420V DC input over the load range.
The result is shown in the table below.
Efficiency vs. Output Power
91.00
91.50
92.00
92.50
93.00
93.50
94.00
94.50
95.00
95.50
96.00
50.00 70.00 90.00 110.00 130.00 150.00 170.00 190.00 210.00 230.00 250.00
Output Power (W)
Efficiency %
350VDC Input
390VDC Input
420VDC Input
Figure 9 - Efficiency plot
Rev. 4.1 6/1/2011 International Rectifier Page 22 of 23
PROPRIETARY INFORMATION - This document and the information contained therein are proprietary and are not to be reproduced, used or disclosed
to others for manufacture or any other purpose except as specifically authorized in writing by
INTERNATIONAL RECTIFIER.
6.7 Thermal Data
The thermal performance of IRS27951 demo board is tested at 400Vdc input and 240W full load at room
temperature.
Part Case Temperature (°C)
MOSFET M1 51
MOSFET M2 48
U1 IRS27951 40
Transformer 69
MOSFET M3 70
MOSFET M4 73
7 Transformer Spec
Minimum operating frequency: 80 kHz
Primary inductance: 600 µH ±10% @1 kHz - 0.25V (Note 1)
Leakage inductance: 125 µH ±10% @1 kHz - 0.25V (Note 2)
Note: 1 Measured between Pins 3 and 6
Note: 2 Measured between Pins 3 and 6 with secondary windings shorted
7.1 Electrical Diagram
7
6
10
15
16
9
13
11
3
6
12
14
TX
Note: pin9 is shorted to pin10 on PCB, pin12 is shorted to pin13 on PCB and pin15 is shorted to pin16 on PCB.
Primar
y
Sec B
Sec C
Sec D
Primar
y
Auxiliary
Sec A
Rev. 4.1 6/1/2011 International Rectifier Page 23 of 23
PROPRIETARY INFORMATION - This document and the information contained therein are proprietary and are not to be reproduced, used or disclosed
to others for manufacture or any other purpose except as specifically authorized in writing by
INTERNATIONAL RECTIFIER.
7.2 Resonant Transformer Winding Position on Coil former
7.3 Resonant Transformer Winding Characteristics
Pins
Winding
Turn number
Wire type [mm]
3 - 6
Primary
36
LITZ - dia. 0.10x60
7 - 6 Auxiliary
2
Dia. 0.2
15 – 12
Sec. A
2
LITZ - dia. 0.10x250
13 - 10
Sec. B
2
LITZ - dia. 0.10x250
11 – 16
Sec. C
2
LITZ - dia. 0.10x250
9 - 14
Sec. D
2
LITZ - dia. 0.10x250
7.4 Resonant Transformer Vender and Part Number
Yu Jing Technology Co., LTD
LP3925H
