Thumb rules for selecting overcurrent values via a gate drive circuit.

Thread Starter


Joined Oct 15, 2014
Hello experts,
I was wondering are there any thumb rules that I need to follow while selecting the overcurrent threshold via the gate driver.
I am currently using the UCC21710 and want to use the dedicated OC pin for over-current detection.
Here is a brief overview of the circuit I got from the Gate driver's website:
The IGBT / SiC that I plan to use is "MSCSM120HM16CTBL3NG", where is Rds(on) is 16mOhm and the maximum drain current in my application is 25 Amps, As of now the OC threshold I am planning to use is 2.31/16mOhm = 144 Amps., which takes into account false triggers generated by the Switching,
My question is , is this on the higher side ? Is there any thumb rule to select the threshold.
In some papers they say that the threshold should be a percentage of the SOA(safe operating area) of the power switch..



Joined Jan 27, 2019
This is not an answer to your question, and it may seem picky but…

For future reference, the English idiom “rules of thumb” doesn’t work as “thumb rules”. Since it is an idiomatic expression, “thumb rules” sounds very strange to a native English speaker.

It is completely logical to use the variation but “rules of thumb” isn’t logical so the conversion doesn’t work as a substitute.

I am only mentioning this to let you know, not as a criticism. Please don’t imagine it is meant to denigrate your English which is otherwise very good, it’s just one of those little things.

I know you’ve been around a while, but I’ve never spoken with you so welcome to AAC, good to have you with us.