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

djmdp · 3rd July 2011, 05:18 PM

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 · 3rd July 2011, 07:12 PM

loose d4 and d5 and try again

regards,
savu

nigelwright7557 · 3rd July 2011, 07:52 PM

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 · 4th July 2011, 07:08 AM

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

djmdp · 5th July 2011, 07:52 PM

Quote:

Originally Posted by 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 · 7th July 2011, 12:53 PM

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

djmdp · 7th July 2011, 01:35 PM

Quote:

Originally Posted by Eva

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 · 8th July 2011, 06:34 PM

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

3rd July 2011, 07:12 PM	#2
savu diyAudio Member Join Date: Feb 2007 Location: Cluj - Napoca	loose d4 and d5 and try again regards, savu __________________ 1'st rule of chess: The only way to get smarter is by playing a smarter opponent.

3rd July 2011, 07:52 PM	#3
nigelwright7557 diyAudio Member Join Date: Apr 2008 Location: Carlisle, England	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. __________________ http://www.murtonpikesystems.co.uk PCBCAD40 pcb design software.

7th July 2011, 12:53 PM	#6
Eva diyAudio Member Join Date: Oct 2003 Location: Near the sea	The purpose of D4 and D5 is not just dead time, they result in a di/dt boost for turn-off (highly desirable). __________________ I use to feel like the small child in The Emperor's New Clothes tale

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4th July 2011, 07:08 AM	#4
djmdp diyAudio Member Join Date: Mar 2011	Ok, I will try it today, and write back at evening.

8th July 2011, 06:34 PM	#8
philuknow diyAudio Member Join Date: Feb 2009	the mur120 you have would do it perfectly, i think, these are fast diodes

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