Re[2]: LF: Protecting a MOSFET driver chip from MOSFET failure?

[Chris Wilson <chris@chriswilson.tv>]

Hello Rik,

Monday, August 10, 2015


> Maybe also worth to mention:  Capacitive coupling of the driver to
> the gate will reduce  the peak voltage at the gate by half (assuming 50% duty 
> cycle).
>  
> The IC driver voltage should be at least 12V in order to ensure  proper 
> switching of the MOSFET.
>  
> If you use a transformer (as suggested by Stefan) one can fiddle
> with  the transformer ratio to get the proper voltage at the gate.
>  
>  
>  
> 73, Rik  ON7YD - OR7T

Hi Rik, thanks for that, I link to a `scope shot of the gate waveform,
taken with a X10 probe, but the `scope does not auto compensate, so an
8V P to P signal I believe? Would that level accept the 50% loss with
capacitive coupling? The pdf for the IRFP450's is also linked. The
capacitors sound an easy mod... But I don't want to upset the apple
cart with ill conceived changes :) Thanks.

http://www.chriswilson.tv/gate_waveform._x10_probe.jpg


http://www.chriswilson.tv/IRFP450.pdf




-- 
Best regards,
 Chris                            mailto:chris@chriswilson.tv