IRS2092S - ringing at gate drive pins - diyAudio
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Old 17th September 2013, 09:34 PM   #1
Shahin is offline Shahin  Canada
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Default IRS2092S - ringing at gate drive pins

Hi all,

This is my first time designing with the IRS2092S and I'm hoping I could get a little guidance. I'm using it along with IRFS4620 FETs. Below is a measurement made with a diff probe on the LO and COM pins.

As you can see there is 65 MHz ringing. Attempts to snub the ringing doesn't affect the ringing frequency which leads me to believe the source is somewhere else.

Feeding the gate of the FETs I have 22R in parallel with 22R + an MMBD1401 diode.

Has anyone else run into this?

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Old 17th September 2013, 09:59 PM   #2
vdij is offline vdij  Moldova
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Put the scheme.
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Old 17th September 2013, 11:27 PM   #3
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A schematic would help but drivers do ring.
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Old 18th September 2013, 12:23 AM   #4
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I wouldn't worry about it too much if the amp is working fine and not overheating.

You could try a snubber using RC tuned to 65MHz.
1/2 PI R C = F.
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Old 18th September 2013, 01:50 AM   #5
tomchr is offline tomchr  United States
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Snubber design: http://www.cde.com/catalogs/igbtAPPguide.pdf

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Old 18th September 2013, 02:05 AM   #6
DUG is offline DUG  Canada
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Physical layout of driver, resistors and FET's for the gate drive path can have an effect of the waveform.

How about a nice clear picture?
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Old 18th September 2013, 08:07 AM   #7
vdij is offline vdij  Moldova
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Do not worry - Wire oscilloscope
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Old 18th September 2013, 01:17 PM   #8
Shahin is offline Shahin  Canada
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Here's the schematic and a screen grab from my layout. The amp is working fine. My only concern is that I'll run into EMI problems.

I was wondering if this was induced by the leads of my diff probe. I'll try floating my scope and using a single ended probe with shorter leads to see if things look any different.

Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.

http://postimg.org/image/6vlxw8j1f/
http://postimg.org/image/vbfuj2sxh/
http://postimg.org/image/6wbrig9it/

Last edited by Shahin; 18th September 2013 at 01:43 PM.
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Old 18th September 2013, 01:53 PM   #9
Shahin is offline Shahin  Canada
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Click the image to open in full size.
screen shot on windows
Click the image to open in full size.
screenshot app
Click the image to open in full size.
program to take screenshots
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Old 18th September 2013, 02:53 PM   #10
vdij is offline vdij  Moldova
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http://www.irf.com/product-info/audi...dtutorial2.pdf can help
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