Crunch BLX-1000D reanimation with IRS20955 gate driver trouble.

[djmdp]

Hello, I'm new in this forum, and sorry for my poor english I have a trouble with this gate driver, something's wrong during high side mosfet OFF, the low side mosfet is ON earlier than high side off. On the simulation there's a PULSE GENERATOR because this crunch amp has own ic pwm gen at 0-15V voltage level, and the vdd voltage for irs will be the same voltage. Maybe someone knows what's the problem with that?

 

[savu]

loose d4 and d5 and try again

regards,
savu

 

[nigelwright7557]

I agree, D4 and D5 arent needed because the chip has a deadtime generator.
If you are still getting shoot through then alter the deadtime.

 

[djmdp]

Ok, I will try it today, and write back at evening.

 

[djmdp]

Ok, I will try it today, and write back at evening.

Hello, finally I've got some new info's. I removed gate diodes, recalculated current sensing for high side mosfet and for the low side (both 24A trip), but it doesn't helped me. I found out that mosfets with higher Rdson (125mohm in this simulation) working so much better but I don't know why is that? Any suggestion? Setting deadtime by tying DT pin to COM hasn't got positive effect on low side on, it working only on high side on.

 

[Eva]

The purpose of D4 and D5 is not just dead time, they result in a di/dt boost for turn-off (highly desirable).

 

[djmdp]

The purpose of D4 and D5 is not just dead time, they result in a di/dt boost for turn-off (highly desirable).

I thought the same when I was placing it on the schematic. So, what's the best didoes for this purpose??

 

[philuknow]

the mur120 you have would do it perfectly, i think, these are fast diodes