ISO5451: Prevent false trigger desat

evs

Part Number: ISO5451

Hi,

I'm planning to redesign my gatedrivers PCB with the ISO5451. Because of component and high voltage clearance, There is some distance between the IGBT and the driver (app. 5cm).

In my current design I have problems with false desat triggers. So I'm looking for a more noise proof/robust solution to prevent this.

Any tips Or how to prevent false triggers?

I assume the key for stable desat signal is a good diode. But there is not much info about that I'm currently using: ES1J from ON semi. That is a fast low capacitance diode so I think i'm good.

Thanks,

EVS

over 7 years ago

0 John Geiger over 7 years ago

TI__Expert 3355 points

Hi evs,

I'm an applications engineer on the high power drivers team and will try to help with this question.

Could you please share your schematic with part values, and a snip of your layout for this part of your circuit? Also, it sounds like you have a system running, so could you share a oscilloscope shot of the DESAT pin and output pin when it's glitching, referencing where your system is in the switching cycle? These bits of information will greatly aid in our ability to provide a thorough answer.

Sections 10.2.2.7 and 10.2.2.8 of the datasheet elaborate on DESAT pin circuit design and protection.

Thanks,
John

0 evs over 7 years ago in reply to John Geiger

Genius 5910 points

John,

Thanks for your help. I resolved it. Turned out the Desat detection was connected on the wrong side of the current sense resistor.

EVS.

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ISO5451: Prevent false trigger desat