IRAC W. IRS27951 Evaluation Board User Guide

Transcription

1 Energy Saving Products 0 N.Sepulveda Blvd, EL Segundo 9045 California, USA IRAC795-0W IRS795 Evaluation Board User Guide Rev //00 International Rectifier Page of 6

2 Table of Contents INTRODUCTION... 3 IRS795/ DESCRIPTION EVALUATION BOARD SPECIFICATIONS Board Description Schematic Evaluation Board Picture Board Component Placement Board PCB Layout Bill of Materials EVALUATION BOARD OPERATING PROCEDURE Load Connection AC/DC Input IRS795 DC Supply Voltage Power-up Sequence SYSTEM PERFORMANCE CHARACTERIZATION Steady-State and Start-up Waveforms Short Circuit Protection Dynamic Load Response & Output Voltage Regulation User Initiated SLEEP Mode Efficiency Chart Thermal Data Transformer Spec Electrical Diagram Resonant Transformer Winding Position on Coil former Resonant Transformer Winding Characteristics... 6 Rev //00 International Rectifier Page of 6

3 INTRODUCTION This document details the test procedure for validation of IRS795 Evaluation Board, featuring the IRS795 Resonant Half Bridge controller HVIC. The document includes schematic diagram, test setup, test procedure, and test results. IRS795/ DESCRIPTION The IRS795 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 80 out-of-p hase for exactly the same time. The IC incorporates additional protection features for robust operation and provides a high performance solution while minimizing external components, design time, and printed circuit board real estate, all in an 8 pin SOIC package. The IC enables the designer to externally program all the following features using a 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. IRS795 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 IRS795 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 V for IRS795 and 3V for IRS795. Finally, the controller IC also features a micro power startup current (I CC <00µA) and a user initiated sleep mode during which the IC power consumption is less than 00µA (@ Vcc=5V). 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 //00 International Rectifier Page 3 of 6

4 3 EVALUATION BOARD SPECIFICATIONS Input Voltage VAC or 400V DC AC Line Frequency Range Hz Converter Switching Frequency Range khz Converter Outputs....4V/6A & V/6A Maximum Output Power...0W Minimum Load Requirement None Maximum Ambient Operating Temperature..40 C Efficiency (@ 0W) % Short Circuit Protection on both Output Rails..... Yes Single Layer PCB with oz Copper There are high voltages present whenever the board is energized and proper precautions should be taken to avoid potential shock and personal injury. 3. Board Description The evaluation board consists of a front-end AC-DC rectifier stage cascaded with a half-bridge resonant DC- DC converter with multiple output voltage rails (4V and V). 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 IRS795 (U) 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 voltages 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. 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, and the output rectifiers are Schottky diodes. The feedback loop is implemented by means of a classical configuration using a TL43 (U3) to adjust the current in the optocoupler TLP6 (U). Weighted resistive dividers from both voltages are summed at the reference node of the TL43 in order to achieve a 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 IRS795 controller IC. A fan is recommended whenever operating at the maximum load for a prolonged period of time. Rev //00 International Rectifier Page 4 of 6

5 better overall output voltage regulation. The optocoupler transistor modulates the current from the RT pin of the controller IC to modulate the switching frequency, thus achieving output voltage regulation. 3. Schematic JP Header 3 F 5A/50V C 0.uF/75V-X 65VAC N RNTC 5 t L Cr Cs DNP R C 0.uF/75V-X B 4 GBU4J-BPMS-ND C3 0.33uF/630V + C4 70uF/450V Rdisch 50K Rstart 70k VCC JP3 Header COM 33uF/35V Rstart 70k CDC VCC uf Rstart3 70k CVcc Dz 8V 00nF CVcc 5k Rvcc RMAX 3.9k RT RSS uf CSS N448 D5 N448 DSS RT 8k 390pF CT CT Dbs MURS60 VCC VB U RT HO CT/SD VS COM LO IRS795 COM HO LO Cbs 0nF Dg N448 Dg N448 Rg Rg Rx DNP STF3NM50N Q Rgs DNP= Do Not Populate DNP Vbus 4.7 Rx STF3NM50N 4.7 Q Rgs VS nf/kv COM W Jumper 60uH.nF/50V U TLP6 VTR TX D V3000S D V3000S COMP DNP=Do not Populate U3 TL43 DNP Rled 5.6k Rbias D3 0TQ040 D4 0TQ040 Rbias.k Cf 00nF Cout Cout6 Rled.k Cf DNP Rf 47k.5mF/5V mf/35v.5mf/5v mf/35v Cout Cout7 Rs5 3.9k Rs4 5k mf/35v Cout3 Rs 33k Rs 0 Rs3 3.74k Lf FB Lf 000uF/5V 3.3uH/0A 3.3uH/0A Cout8 mf/35v Cout4 00nF 00nF 470 Cout5 Cout9 560 Rprl Rprl 4V COM V COM JP4 Header 6 JP5 Header 6 Figure Evaluation Board Schematic Rev //00 International Rectifier Page 5 of 6

6 3.3 Evaluation Board Picture Figure Evaluation Board Photo 3.4 Board Component Placement Figure 3 Evaluation Board Component Placement Rev //00 International Rectifier Page 6 of 6

7 3.5 Board PCB Layout Figure 4 - Board Bottom Layer Copper Rev //00 International Rectifier Page 7 of 6

8 3.6 Bill of Materials Designator Description Quantity Value/Rating Vendor Part# B Single Phase Bridge Rectifier 600V/4A DIGIKEY GBU4J-BPMS-ND C, C X Safety Capacitor 00nF/75VAC DIGIKEY P054-ND C3 Metal Poly Capacitor 0.33uF/630V DIGIKEY P45-ND C4 Electrolytic Bulk Capacitor TS-HC 70uF/450V DIGIKEY EET-HCW7LA Cbs 06 General Purpose Ceramic SMD 0nF/50V DIGIKEY ND Cf, Cout5, Cout9, CVcc 06 General Purpose Ceramic SMD 4 00nF/50V DIGIKEY ND CDC Electrolytic Capacitor FM Radial 33uF/35V DIGIKEY P3475-ND Cf Not Used Cout, Cout, Cout3, Cout4 Aluminium Electrolytic Capacitor 05 C 4 000uF/35V DIGIKEY ND Cout6, Cout7 Aluminium Electrolytic Capacitor 05 C 500uF/5V DIGIKEY ND Cout8 Aluminium Electrolytic Capacitor 05 C 000uF/ 5V DIGIKEY ND Cr Polypropylene Capacitor High Ripple nf/kv DIGIKEY ND Cs 50VAC Y Safety Ceramic Disc Capacitor.nF/50V DIGIKEY ND CSS, CVcc 06 General Purpose Ceramic SMD uf/5v DIGIKEY ND CT 06 General Purpose Ceramic SMD ±5% 390pF/50V DIGIKEY ND D, D TO0AB Power Schottky Rectifier 00V/30A DIGIKEY V3000S-E3/45GI-ND D3, D4 TO0AC Power Schottky Rectifier 40V/0A DIGIKEY 0TQ040PBF-ND D5, Dg, Dg, DSS Fast Recovery Diode DO V/0.3A DIGIKEY N448DICT-ND Dbs Fast Recttifier diode SMB 600V/A DIGIKEY MURS60-FDICT-ND Dz Zener Diode SMD 8V/0.5W DIGIKEY FLZ8VCCT-ND F FUSE IEC FA LBC 5x0 50V/5A DIGIKEY F395-ND JP CONN HEADER 3POS 0.56 VERT TIN DIGIKEY WM46-ND JP3 CONN HEADER POS 0. VERT TIN DIGIKEY WM400-ND JP4, JP5 CONN HEADER 6POS 0.56 VERT TIN DIGIKEY WM464-ND L EMI Common Mode Choke 6mH/.6A DIGIKEY ND Lf, Lf PCV Series Drum Core Inductor 0mm 3.3uH/0A COILCRAFT PCV033-0L Q, Q TO-0FP N-Channel Power MOSFET 500V/A DIGIKEY STF3NM50N R, Rbias, Rgs, Rgs Not Used Rbias, Rled 06 SMD Film RED /4W %.k DIGIKEY RHM.0kFCT-ND Rdisch Metal Film Power Resistor W 5% 50k DIGIKEY BC50KW -CT-ND Rf 06 SMD Film RED /4W % 47k DIGIKEY RHM47.0kFCT-ND Rg, Rg 06 SMD Film RED /4W % DIGIKEY RHM.0FCT-ND Rled 06 SMD Film RED /4W % 5.6k DIGIKEY RHM5.60kFCT-ND RMAX 06 SMD Film RED /4W % 5k DIGIKEY RHM5.0kFCT-ND RNTC Inrush Current Limiter 5 DIGIKEY ND Rprl Metal Film Power Resistor W 5% 560 DIGIKEY PPC560W -CT-ND Rprl Metal Film Power Resistor W 5% 470 DIGIKEY PPC470W -CT-ND Rs 06 SMD Film RED /4W % 33k DIGIKEY RHM33.0KFCT-ND Rs 06 SMD Film RED /4W % 0 DIGIKEY P0.0ECT-ND Rs3 06 SMD Film RED /4W % 3.74k DIGIKEY RHM3.74KFCT-ND Rs4 06 SMD Film RED /4W % 5k DIGIKEY RHM5.0KFCT-ND Rs5, RSS 06 SMD Film RED /4W % 3.9k DIGIKEY RHM3.90KFCT-ND Rstart, Rstart, Rstart3 06 SMD Film RED /4W % 3 70k DIGIKEY RHM70KFCT-ND RT 06 SMD Film RED /4W % 8k DIGIKEY RHM8.0KFCT-ND Rvcc 06 SMD Film RED /4W % DIGIKEY RHM.0FCT-ND Rx, Rx 06 SMD Film RED /4W % 4.7 DIGIKEY FRCT-ND TX Resonant Power Transformer ETD49 PRECISION INC R U IRS795 Control IC IR IRS795S U Photocoupler TRANS-OUT 4-DIP TLP6 DIGIKEY TLP6FT-ND U3 Programmable Voltage Regulator SOT3-3 TL43 DIGIKEY ND W Jumper for Primary Current Sensing Loop AWG0 Rev //00 International Rectifier Page 8 of 6

9 4 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. Variable AC or HV DC Source (Variac or Electronic) Electronic or Resistive Load 4V/6A ISOLATION TRANSFORMER Electronic or Resistive Load V/6A DC Power Supply Figure 5 - Recommended Evaluation Board Test Setup 4. Load Connection Connect a resistive or electronic load, capable of 50W continuous power on the 4V rail to connector JP4 and a 75W continuous power load on the V output rail to JP5. Please note that there is no minimum load 3 requirement for this board. 3 A minimum load has been added on both the output rails to ensure tight voltage regulation for both output rails from no load to full load. Rev //00 International Rectifier Page 9 of 6

10 4. AC/DC Input The use of 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 a 60Hz AC power source capable of operation up to 80VAC or a 400V DC source to JP. The converter can keep the output regulated when the BUS voltage is in the range of 350V DC to 40V 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. 4.3 IRS795 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. If you choose to supply VCC voltage using external DC power supply (in order to study IC VCC UVLO features etc.) then simply provide DC voltage to connector JP3 or alternatively between Test Points V CC and COM. You should also dis-connect Rvcc and Rstart in order to measure the Vcc supply current from the DC source. The minimum supply voltage recommended is V while a maximum voltage of 8V can be applied without damaging the IC. The location of the DC power connector and controller IC is shown in Figure 6. IRS795 and control components on bottom layer VCC COM Figure 6 - VCC connector and test points 4.4 Power-up Sequence Once all the connections are made, the system can be powered up. When using external DC supply to bias Vcc, power-up the AC supply or 400V DC supply first and then the Vcc circuitry. This sequence is necessary to ensure soft start operation of the DC-DC converter. Rev //00 International Rectifier Page 0 of 6

11 5 SYSTEM PERFORMANCE CHARACTERIZATION Test Conditions V IN =400V DC; Full Load (4V/6A, V/6A); No Load (4V/0A, V/0A) 5. Steady-State and Start-up Waveforms Ch : Low-side device V GS Ch 3: Voltage at VS pin Ch 4: Resonant tank current Full Load Operation No Load Operation Full Load Start-up No Load Start-up Rev //00 International Rectifier Page of 6

12 5. Short Circuit Protection IRS795 uses high-voltage technology to sense the current in the low-side MOSFET. The voltage at the VS node is sensed when the low-side device is turned ON and the system shuts off when a load short-circuit condition is sensed (i.e. I D *R DSON exceeds the fixed internal threshold). In this reference design, IRS795 latched shutdown when primary current exceed 8.9A peak. Ch : V Rail Output Voltage Ch 3: V Rail Output Voltage Ch 4: Resonant tank current 4V Rail short-circuit V Rail short circuit Rev //00 International Rectifier Page of 6

13 5.3 Dynamic Load Response & Output Voltage Regulation A load step from full load to no load and no load to full load was applied to test the dynamic response of the system. The output voltage is tightly regulated within a 3% regulation band over the entire line load range. A summary of the load performance is also shown below. Ch 3: 4V Rail output voltage Ch : V Rail output voltage Ch 4: Resonant tank current No Load to Full Load Step Full Load to No Load Step Load Regulation Vout (V) V Output 4V Output Iout (A) Figure 7 - Output voltage regulation plot Rev //00 International Rectifier Page 3 of 6

14 5.4 User Initiated SLEEP Mode The CT/SD pin of IRS795 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 : Low-side device V GS Ch : CT/SD pin of IRS795 Ch 3: High-side device V GS Ch 4: Resonant tank current Sleep mode initiated by externally pulling the CT/SD pin to COM 5.5 Efficiency Chart The efficiency of IRS795 demo board was tested at both 70Vac input and 400Vdc input over the load range. The result is shown in the table below. 4Vout 4V current(a) Vout V current (A) 70Vac 400Vdc Pout(W) Efficiency Efficiency % 9.0% % 9.6% % 9.9% % 9.7% % % Rev //00 International Rectifier Page 4 of 6

15 The average efficiency of the board at 5%, 50%, 75% and 00% load is 9% at 70Vac input: 93.5% 93.0% Efficieny vs. Output Power Efficiency 9.5% 9.0% 9.5% 9.0% 90.5% 400Vdc input 70Vac input Output Power (W) Figure 8 - Efficiency plot 5.6 Thermal Data The thermal performance of IRS795 demo board is tested at 400Vdc input and 0W full load under room temperature. Part Case Temperature ( C) MOSFET Q 44.5 MOSFET Q 4.5 U IRS795 4 Transformer 73 4V diodes 7 V diodes 60 6 Transformer Spec Core type: ETD49-0R44949EC Minimum operating frequency: 80 khz Primary inductance: 585 µh khz - 0.5V (Note ) Leakage inductance: 5 µh khz - 0.5V (Note ) Note: Measured between Pins and 5 Note: Measured between Pins and 5 with secondary windings shorted Rev //00 International Rectifier Page 5 of 6

16 6. Electrical Diagram 9 TX 0 Auxiliary Sec A Sec B Primar 5 3 Sec C Sec D Note: pin9 is shorted to pin8 on PCB, pin3 is shorted to pin on PCB. 6. Resonant Transformer Winding Position on Coil former 6.3 Resonant Transformer Winding Characteristics Pins Winding Turn number RMS Current Wire type [mm] - 5 Primary 36.8A LITZ - dia. 0.5x Auxiliary 0.A Dia Sec. A 4 7A LITZ - dia. 0.0x Sec. B 4 7A LITZ - dia. 0.0x Sec. C 7A LITZ - dia. 0.0x40 - Sec. D 7A LITZ - dia. 0.0x40 Rev //00 International Rectifier Page 6 of 6