Energy Saving Products 101 N.Sepulveda Blvd, EL Segundo 90245 California, USA IRAC27951SR IRS27951 Evaluation Board User Guide Rev. 4.1 6/1/2011 International Rectifier Page 1 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. 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 Rev. 4.1 6/1/2011 International Rectifier Page 2 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. 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 RDSON 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 (ICC<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. Rev. 4.1 6/1/2011 International Rectifier Page 3 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. 3 IR11682 DESCRIPTION IR11682 is a secondary-side SmartRectifierTM 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 VTH2. When VTH2 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 VTH1. Once the threshold is crossed, the current will start flowing again through the body diode, causing the VDS voltage to jump negative. Hence, VTH2 is blanked for a time duration tBLANK after VTH1 is triggered. When the device VDS crosses the positive reset threshold VTH3, tBLANK is terminated and the IC is ready for next conduction cycle as shown below. VTH3 IDS VDS T1 T2 VTH1 VTH2 Gate Drive Blanking MOT tBLANK time 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 Rev. 4.1 6/1/2011 International Rectifier Page 4 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. 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°C2 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 DCDC 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. Rev. 4.1 6/1/2011 International Rectifier Page 5 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. 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 dualchannel SmartRectifierTM 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 turnoff 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 Rev. 4.1 6/1/2011 International Rectifier Page 6 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. 4.3 Evaluation Board Picture Figure 2 – Evaluation Board Photo 4.4 Board Component Placement Figure 3 – Evaluation Board Top Side Component Placement Rev. 4.1 6/1/2011 International Rectifier Page 7 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. 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 Rev. 4.1 6/1/2011 International Rectifier Page 8 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. 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 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 2N3904-APCT-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 RHM5.60KFCT-ND Rled1 1206 SMD Film RED 1/ 4W 1% 1 5.6k DIGIKEY 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 LP3925H TX Resonant Power Transformer 1 TRANSYJ YUJING 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 Rev. 4.1 6/1/2011 International Rectifier Page 9 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. 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. ISOLATION TRANSFORMER Variable AC or HV DC Source (Variac or Electronic) Electronic or Resistive Load 24V/10A Figure 7 - Recommended Evaluation Board Test Setup 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 load3 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. Rev. 4.1 6/1/2011 International Rectifier Page 10 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. 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 Rev. 4.1 6/1/2011 International Rectifier Page 11 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 SYSTEM PERFORMANCE CHARACTERIZATION 6.1 Steady-State and Start-up Waveforms Test Conditions – VIN = 350V DC; Full Load (24V/10A); No Load (24V/0A) Ch 1: Low-side device VGS – 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. Rev. 4.1 6/1/2011 International Rectifier Page 12 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. Test Conditions – VIN = 390V DC; Full Load (24V/10A); No Load (24V/0A) Ch 1: Low-side device VGS – 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. Rev. 4.1 6/1/2011 International Rectifier Page 13 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. Test Conditions – VIN = 420V DC; Full Load (24V/10A); No Load (24V/0A) Ch 1: Low-side device VGS – 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 Rev. 4.1 6/1/2011 No Load Start-up International Rectifier Page 14 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. 6.2 Synchronous Rectifier Waveform Ch 1: SR gate1 – Ch 2: SR gate2 Ch 2: Voltage at VS pin – Ch 4: Resonant tank current Rev. 4.1 350Vdc, No Load Operation 350Vdc, Full Load Operation 385Vdc, Full Load Operation 420Vdc, Full Load Operation 6/1/2011 International Rectifier Page 15 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. 6.3 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 Rev. 4.1 6/1/2011 Full Load to No Load Step at 350Vdc International Rectifier Page 16 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. Load Step at 390Vdc input No Load to Full Load Step at 390Vdc Rev. 4.1 6/1/2011 Full Load to No Load Step at 390Vdc International Rectifier Page 17 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. Load Step at 420Vdc input No Load to Full Load Step at 420Vdc Rev. 4.1 6/1/2011 Full Load to No Load Step at 420Vdc International Rectifier Page 18 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. 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 24.00 23.90 23.80 Vout (V) 23.70 23.60 350 VDC Input 23.50 390 VDC Input 23.40 420 VDC Input 23.30 23.20 23.10 23.00 0.00 2.00 4.00 6.00 8.00 10.00 Iout (A) 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. Rev. 4.1 6/1/2011 International Rectifier Page 19 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. 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 VGS Ch 2: CT/SD pin of IRS27951 Ch 3: High-side device VGS Ch 4: Resonant tank current Sleep mode initiated by externally pulling the CT/SD pin to COM Rev. 4.1 6/1/2011 International Rectifier Page 20 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. 6.6 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 96.00 95.50 95.00 Efficiency % 94.50 94.00 350VDC Input 93.50 390VDC Input 93.00 420VDC Input 92.50 92.00 91.50 91.00 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) Figure 9 - Efficiency plot Rev. 4.1 6/1/2011 International Rectifier Page 21 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 MOSFET M1 MOSFET M2 U1 IRS27951 Transformer MOSFET M3 MOSFET M4 Case Temperature (°C) 51 48 40 69 70 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 TX 16 Sec C Auxiliary 6 3 11 12 15 10 Primary Sec A Sec B 6 13 14 9 Sec D Note: pin9 is shorted to pin10 on PCB, pin12 is shorted to pin13 on PCB and pin15 is shorted to pin16 on PCB. 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. Primary 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 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.