Guru
Joined: 21/06/2018
Location: AustraliaPosts: 1285
| Posted: 08:12am 12 Feb 2026 |
The gate resistors for the HY5608's that I got very good results with are 1R2.
I did not get any noticeable improvement by adding diodes across the resistors.
I did use a 12V - 15V low side DC/DC module to provide the negative bias of ~ 3V there was no shoot through at all. The two capacitors across each of the inverse optocoupler LEDs is listed as 1nF, in the 16 FET Power board I used 1n5, maybe 1n is a bit on the small side. The capacitors are proportional to the "dead time" between upper and lower FETs.
If the gate resistor values are too high Miller can try to turn on the FET when it should be off.
The combination of 1R2 low impedance drive and -3V Gate bias has served me well in my builds. Although I did not notice any issues with no negative 3V bias, I do like the belts and braces approach and extra safety margins afforded by using the -3V bias.
If the Wiseguy small FET board was one supplied from me ages ago maybe I put the wrong resistor values in as I had initially decided to just use HY4008's ? They look like 3R3 from the picture?