Guru
Joined: 02/02/2017
Location: AustraliaPosts: 1470
| Posted: 02:05am 09 Feb 2026 |
things have changed after fitting the 10R resistor (I had no 4R7)
first, just the resistor:
and
the high frequency ringing is gone. as are the fast gate voltage slopes.
This is to be expected, less current into the capacitance of the FET gate will
mean slower rise and fall times.
And look at the second peaks. this is new to me.
I think the diodes will help with those.
now I also add 1N5819 diodes. These are Schottky type and switch fast, and
a voltage drop of about 0.5V
and
now the gate voltages (and therefore the switching performance of the FETs)
are looking good. I see very low voltage on the LOW side FET gate after
the high side FET switches on, pulling the inverter output up to DC supply voltage.
This is when shoot through is most likely.
there still is some high frequency voltage on the high side gate and this is when we
start thinking about ferrite beads.