Guru
Joined: 08/02/2015
Location: New ZealandPosts: 1204
| Posted: 08:08am 09 Feb 2026 |
That small cap (ceramic) is a very low impedance and can absorb some of the miller pulse getting back into the gate; too large and its going to stress out your driver chip...
AS an experiment: remove the gate drive resistor to one of the L0 mosfets, short the gate directly to its source pin via a similar resistor, this removes the inductance and any transmission line affect back to the driver IC.
Power it up, yeah the output wave form will be crap, but place your scope probe across the shorting resistor, see what gets reflected back by the miller effect as the H0 mosfet turns on; if the wave form is heaps better, then you know its circuit board layout dynamics affecting the gate drive, perhaps necessitating a better layout.
Aim to have the output of the mosfet driver 5-10mm or so from the gate pin, remember the gate circuit is a transmission line, the longer and thinner it is, the more time it takes for the driver transition to get to the gate, similarly a miller pulse getting into the gate from H0 mosfet turning on, takes longer to be negated by the impedance of the driver sitting at 0 volts.
Edited 2026-02-09 18:27 by Solar Mike