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SiC MOSFET Isolated Gate Driver

SiC MOSFET Isolated Gate Driver

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:

•

Thecircuitboardhasbeenextendedsothatnow2wattaswellas1watt

DC-DC converters can be used. This enables driving larger MOSFETs or driving

of smaller MOSFETs at higher frequency.

•

Thecreep/strikeclearancehasbeensignificantlyincreased.

•

Aseparateregulatorhasbeenaddedfortheopto-isolator.Thisallowssimpler

bypassing of the DC-DC converters when non-isolated operation is desired.

•

Theoutputresistornetworkhasbeenmodifiedwithanadditionaldiodeto

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

ofthecomponentsarenotpopulatedbecauseoftheaddedflexibilityinsettinguptheoutput

network.

The new schematic for the enhanced gate driver is shown in Figure 3. The circuit consists of

twoisolatedDC-DCconverters(X2andX3),anopto-isolator(U1)andthegatedriverinte-

gratedcircuit(U2).Thisintegratedcircuit,theClare/IXYSIXDN609SIcanprovide35Voutput

swingandupto9Aofcurrentwithatypicaloutputresistanceof0.8Ω.Theopto-isolator,

theAvagoACPL-4800-300E,hashighcommonmodetransientimmunity(30kV/µsec)andcan

operatefrom4.5to20V.Aprovisionforaninputfilteringcapacitor(C4)hasbeenincluded

if needed. Power is provided by isolated DC-DC converters; one for the positive bias and the

otherfornegativebias.X2andX3arebothfromtheRecomRPseriesof1wattunregulated

isolatedDC-DCconvertersortheRecom[1]RxxP2xxseriesof2wattDC-DCconverters.Ei-

ther type can be accommodated depending on the application.

Figure 1: Isolated Gate Driver Top View

Figure 2: Isolated Gate Driver Bottom View