SiC MOSFET Isolated Gate Driver SiC MOSFET Isolated Gate Driver Bob Callanan, Cree Inc This article describes an implementation of an isolated gate driver suitable for testing and evaluating SiC MOSFETs in a variety of applications. This design replaces previous versions of this application note and include new enhancements. The enhancements are as follows: * * * * The circuit board has been extended so that now 2 watt as well as 1 watt DC-DC converters can be used. This enables driving larger MOSFETs or driving of smaller MOSFETs at higher frequency. The creep/strike clearance has been significantly increased. A separate regulator has been added for the opto-isolator. This allows simpler bypassing of the DC-DC converters when non-isolated operation is desired. The output resistor network has been modified with an additional diode to allow separate optimization of turn-on and turn-off transitions. The top and bottom view of the enhanced gate driver is shown in Figures 1 and 2. The enhanced creep distance is accomplished with the groove in the printed circuit card. Some of the components are not populated because of the added flexibility in setting up the output network. VB CPWR-AN10, RE r ated Gate Drive ol Is ET SF MO SiC Figure 1: Isolated Gate Driver Top View Figure 2: Isolated Gate Driver Bottom View The new schematic for the enhanced gate driver is shown in Figure 3. The circuit consists of two isolated DC-DC converters (X2 and X3), an opto-isolator (U1) and the gate driver integrated circuit (U2). This integrated circuit, the Clare/IXYS IXDN609SI can provide 35V output swing and up to 9A of current with a typical output resistance of 0.8 . The opto-isolator, the Avago ACPL-4800-300E, has high common mode transient immunity (30kV/sec) and can operate from 4.5 to 20V. A provision for an input filtering capacitor (C4) has been included if needed. Power is provided by isolated DC-DC converters; one for the positive bias and the other for negative bias. X2 and X3 are both from the Recom RP series of 1 watt unregulated isolated DC-DC converters or the Recom [1] RxxP2xx series of 2 watt DC-DC converters. Either type can be accommodated depending on the application. Subject to change without notice. www.cree.com 1 These converters are inexpensive with an isolation voltage rating of 5.2kV and also have very low isolation capacitance. In this particular configuration, X2 is a 12V in 5V out converter and X3 is a 12V in, +/-12V out converter. As shown in the schematic, the outputs of the converters are series connected and the common connection is referenced to the source terminal. Therefore, VCC determines the gate pulse positive voltage and -VEE determines the negative gate pulse voltage. The -VEE node is used as the ground reference for opto-isolator and the gate driver. The opto-isolator's maximum operating voltage is 20V which can be greater than the voltage appearing at VCC. An emitter follower clam consisting of Q1 and D1 has been added to limit the voltage to the opto-isolator to 17.3V nominal. A base resistor (R16) was included if additional dampening is desired for the emitter follower. In practice, a zero ohm resistor works fine. Resistors R2, R4, R5, R9-R15 and diode D2 can be populated to provide optimum turn-on and turn-off performance. In this case, only R2, R4 and R5 are populated with 20 ohm 1/3 watt resistors. To minimize stray inductance, capacitors C8C10 are located very close to the source output pin and the gate driver to provide very tight coupling between the source output terminal and the -VEE node. Figure 3: Isolated Gate Driver Schematic 0.100" ISOLATION BOUNDRY SLIT BOARD IF REQ. R15 THESE COMPONENTS ARE LOCATED ON THE -VEE PLANE R14 +VCC X3 1 VCC HIGH +VIN +VOUT COM 2 VCC HIGH RTN -VIN -VOUT R13 C1 1U 0603 7 6 5 R1 10K 0805 R16 0 C2 1U 0603 RP-1212D 0805 VCC LOW 2 VCC LOW RTN +VIN -VIN +VOUT -VOUT SOURCE 5 RP-1205S R6 620 INPUT LOW 0805 J2 1 C4 TBD 0805 2 3 4 NC HEADER 6 VCC ANODE NC CATH NC VO GND VCC HIGH RTN INPUT HIGH INPUT LOW VCC LOW VCC LOW RTN 20 R11 20 1210 R10 20 1210 R9 20 1210 R2 20 1210 R4 20 1210 R5 20 1210 -VEE -VEE 8 7 6 +VCC C5 100N 0805 5 ACPL-4800-300E VCC HIGH 1 2 3 4 5 6 -VEE U1 R3 620 INPUT HIGH 0805 C3 1U 0603 7 20 20 D2 DIODE Q1 DXT2222A D1 MMSZ5248B-7-F X2 1 R12 20 -VEE 1 2 R7 47K 0603 -VEE C6 100N 0805 3 4 -VEE +VCC U2 VCC VCC IN OUT NC OUT GND GND IXDN609SI 8 7 6 5 C7 4.7U 1206 -VEE GATE JP1 R8 47K 0603 C8 -VEE -VEE -VEE 7 8 9 HEADER 3 JP2 10 11 12 10N 1210 C9 HEADER 3 SOURCE 100N C10 10U 1210 SOURCE Operation of the gate driver is as follows. A +10 to +12V pulse is applied to the opto causes the gate terminal to go high. The intent of this circuit is to afford the maximum flexibility. Therefore, unregulated DC-DC converters were used so that the output gate pulse positive and negative voltage levels can be adjusted at ground level. The gate voltage positive level is adjusted by varying the voltage between the VCC HIGH and VCC HIGH RTN and the negative pulse level is adjusted by varying the voltage between the VCC LOW and VCC LOW RTN pins. The procedure is to observe the output of the gate driver board with an oscilloscope and adjust VCC HIGH and VCC LOW input voltages until the gate pulse is set to the desired values. Care must be taken during adjustment to insure that the voltage between the VCC and -VEE nodes does not exceed the maximum ratings of U2, which is 35V. CPWR-AN10, REV -B 2 SiC MOSFET Isolated Gate Driver This document is provided for informational purposes only and is not a warranty or a specification. For product specifications, please see the data sheets available at www.cree.com/power. For warranty information, please contact Cree Sales at PowerSales@cree.com. The circuit can be modified to remove the isolated DC-DC converters to allow direct connection of VCC, source, and -VEE directly to external power supplies. This is accomplished by removing the converters and replacing them with jumper wires. The schematic of this change is shown in Figure 4. Notice that X2 and X3 have been removed and replaced by jumpers shown as the dark blue nets. Also note, the gate driver can also be configured for no negative gate bias by not populating the negative gate bias DC/DC converter as shown in Figure 5. Notice that DC-DC converter X3 is not populated and a jumper is placed as shown in the dark blue net. Non-regulated DC-DC converters are used in this design to allow convenient adjustment of the high and low gate pulse amplitudes at ground level. The VCC high input sets the high level and the VCC low input sets the low level. The procedure is to observe the output of the gate driver board with an oscilloscope and adjust VCC high and VCC low until the output pulse high and low levels are set to the desired values. Figure 4: Non-Isolated Configuration Schematic 0.100" ISOLATION BOUNDRY SLIT BOARD IF REQ. R15 THESE COMPONENTS ARE LOCATED ON THE -VEE PLANE R14 +VCC R13 C1 1U 0603 VCC HIGH NC R1 10K 0805 R16 0 C2 1U 0603 VCC HIGH RTN R12 0805 C3 1U 0603 VCC LOW SOURCE -VEE 20 20 20 D2 DIODE Q1 DXT2222A D1 MMSZ5248B-7-F 20 R11 20 1210 R10 20 1210 R9 20 1210 R2 20 1210 R4 20 1210 R5 20 1210 -VEE VCC LOW RTN -VEE U1 R3 620 1 INPUT HIGH 0805 R6 620 INPUT LOW 0805 J2 C4 TBD 0805 2 3 4 NC ANODE NC CATH NC HEADER 6 VO GND 8 7 6 +VCC C5 100N 0805 5 ACPL-4800-300E VCC HIGH 1 2 3 4 5 6 VCC -VEE 1 2 R7 47K 0603 -VEE C6 100N 0805 3 4 -VEE +VCC U2 VCC VCC IN OUT NC OUT GND GND 8 7 6 5 IXDN609SI VCC HIGH RTN C7 4.7U 1206 -VEE INPUT LOW -VEE VCC LOW VCC LOW RTN JP1 R8 47K 0603 C8 -VEE INPUT HIGH GATE -VEE 7 8 9 HEADER 3 JP2 10 11 12 10N 1210 C9 HEADER 3 SOURCE 100N C10 10U 1210 SOURCE R9 CPWR-AN10, REV -B 3 SiC MOSFET Isolated Gate Driver This document is provided for informational purposes only and is not a warranty or a specification. For product specifications, please see the data sheets available at www.cree.com/power. For warranty information, please contact Cree Sales at PowerSales@cree.com. Figure 5: Isolated Configuration Schematic - No Negative Bias 0.100" ISOLATION BOUNDRY SLIT BOARD IF REQ. R15 THESE COMPONENTS ARE LOCATED ON THE -VEE PLANE R14 +VCC X3 1 VCC HIGH +VIN +VOUT COM 2 VCC HIGH RTN -VIN -VOUT R13 C1 1U 0603 7 6 5 R1 10K 0805 R16 0 C2 1U 0603 RP-1212D R12 C3 1U 0603 VCC LOW SOURCE -VEE 20 20 20 D2 DIODE Q1 DXT2222A 0805 D1 MMSZ5248B-7-F 20 R11 20 1210 R10 20 1210 R9 20 1210 R2 20 1210 R4 20 1210 R5 20 1210 -VEE VCC LOW RTN -VEE U1 R3 620 1 INPUT HIGH 0805 R6 620 INPUT LOW 0805 J2 C4 TBD 0805 2 3 4 NC ANODE NC CATH NC HEADER 6 VO GND 8 7 6 VCC HIGH RTN INPUT HIGH INPUT LOW VCC LOW VCC LOW RTN +VCC C5 100N 0805 5 ACPL-4800-300E VCC HIGH 1 2 3 4 5 6 VCC -VEE 1 2 R7 47K 0603 -VEE C6 100N 0805 3 4 -VEE +VCC U2 VCC VCC IN OUT NC OUT GND GND IXDN609SI 8 7 6 5 C7 4.7U 1206 -VEE GATE JP1 R8 47K 0603 C8 -VEE -VEE -VEE 7 8 9 HEADER 3 JP2 10 11 12 10N 1210 C9 HEADER 3 SOURCE 100N C10 10U 1210 SOURCE The bill of materials for the isolated gate driver is shown in Table 1. Please note that different Recom isolated DC-DC converters can be used. Also note that the photographs of the populated board shown in Figures 1 and 2 are for reference only and does not correlate to this BOM. Also, C4, D2 and R9-R15 are not populated so they are listed as TBD. It is up to the user to select these parts depending on the application. CPWR-AN10, REV -B 4 SiC MOSFET Isolated Gate Driver This document is provided for informational purposes only and is not a warranty or a specification. For product specifications, please see the data sheets available at www.cree.com/power. For warranty information, please contact Cree Sales at PowerSales@cree.com. Table 1: Isolated Gate Driver Bill of Materials Item Quant. Ref. Des. Value Description Manufacturer Manufacturer P/N 1 3 C1,C2,C3 1U Capacitor, Ceramic 1UF 25V X5R 0603 AVX 06033D105MAT2A 2 1 C4 TBD Capacitor, Ceramic TBD 0805 3 2 C5,C6 100N Capacitor, Ceramic 100n 50V X7R 0805 Kemet C0805C104K5RACTU 4 1 C7 4.7U Capacitor, Ceramic 4.7UF 50V X5R 1206 Kemet C1206C475K5PACTU 5 1 C8 10N Capacitor, Ceramic 10n 50V NP0 Kemet 1210 C1210C103J5GACTU 6 1 C9 100N Capacitor, Ceramic 100n 50V X7R 1206 Kemet C1206C104K5RACTU 7 1 C10 10U Capacitor, Ceramic 10UF 16V X5R 1210 Kemet C1210C106K4PACTU 8 1 D1 MMSZ5248B7-F DIODE ZENER 18V 500MW SOD- Diodes Inc. 123 9 1 D2 DIODE Diode, TBD SOD-123AC 10 2 JP1,JP2 HEADER 3 3 Pins Cut to length Sullins Connector Solutions PBC36SAAN 11 1 J2 HEADER 6 6 Pins Cut to length Sullins Connector Solutions PBC36SAAN 12 1 Q1 DXT2222A Transistor, NPN General Purpose, Diodes Inc. 40V SOT-23 DXT2222A-13 13 1 R1 10K Resistor, 10k 1/8W 5% 0805 Vishay/Dale CRCW080510K0JNEA 14 3 R2,R4,R5 20 Resistor, 20 Ohm 1/3W 5% 1210 Vishay/Dale CRCW121020R0JNEA 15 7 R9-R15 TBD Resistor, TBD 1/3W 5% 1210 16 2 R3,R6 620 Resistor, 620 Ohm 1/8W 5% 0805 Vishay/Dale CRCW0805620RJNEA 17 2 R7,R8 47K Resistor, 47k 1/10W 5% 0603 Vishay/Dale CRCW060347K0JNEA 18 1 R16 0 Resistor, 10k 1/8W 5% 0805 Vishay/Dale CRCW08050000Z0EA 19 1 U1 ACPL-4800300E Opto-Isolator Avago ACPL-4800-300E 20 1 U2 IXDN609SI Gate Driver Non-Inverting IXYS IXDN609SI 21 1 X2 RP-1205S DC/DC Converter, 1W 12V in Recom RP-1205S Recom RP-1212D MMSZ5248B-7-F 5V out 22 1 X3 RP-1212D DC/DC Converter, 1W 12V in +/-12V out 23 1 - - ISOLATED GATE DRIVER REV5 PCB Cree [1] http://www.recom-power.com/ Copyright (c) 2012 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree, the Cree logo, and Zero Recovery are registered trademarks of Cree, Inc. This document is provided for informational purposes only and is not a warranty or a specification. This product is currently available for evaluation and testing purposes only, and is provided "as is" without warranty. For preliminary, non-binding product specifications, please see the preliminary data sheet available at www.cree.com/power. 5 CPWR-AN10, REV -B SiC MOSFET Isolated Gate Driver Cree, Inc. 4600 Silicon Drive Durham, NC 27703 USA Tel: +1.919.313.5300 Fax: +1.919.313.5451 www.cree.com/power Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: Cree, Inc.: CRD-001