How to GaN 04a - Gate Drivers for Gallium Nitride (GaN) FETs

[@twostickes]

A great overview of GaN driving, well beyond a simple intro!

[@EPCCorporation]

Glad you liked it!

[@infiniteefpv]

Hey, at 18:27, doesn't the bootstrap diode on the high side mean that there is a significant difference in drive voltage between the high side and low side (due to the Vf of the diode)? Does this cause problems?

[@EPCCorporation]

A voltage drop would occur, but there is a nice cancellation of the drops in 2 of the diodes, resulting in the upper gate drive being approximately the same as the bottom: 1) As you mentioned, the top boost diode, Dbstst, drops voltage. So, the output is about 5V - 0.7 V = 4.3 V. 2) But, the reference point of the upper gate drive is the switch node. And, during the dead times, the bottom FET’s body diode (and, in this case, the parallel diode Dap) have a drop. So, during the dead time the switch node is below ground. About 1 V below ground in this case. These diode drops offset each other. Resulting in the upper gate drive voltage in many cases being the same or even higher than the bottom gate driver voltage. The Zener Dclmp helps in case the upper gate voltage floats too high. If you have additional questions please visit the Support Forum (forum.epc-co.com/) or Ask a GaN Expert (epc-co.com/epc/Contact/AskaGaNExpert.aspx) Thank you!

[@seba7sass]

Hello. Is there a contact for a formal question? I have been working with GaN and I am having some complications with a peak voltage at turn off.

[@EPCCorporation]

Yes. Please use our "Ask a GaN Expert" support function on the EPC website here: epc-co.com/epc/contact/ask-a-gan-expert