Basics of DESAT over-current protection

[@xinpengyang-dz5rt]

Thanks for your teaching. I have a question: Should DESAT protection only be used on the low-side switch? Should I use this protection on the high-side switch as well?

[@sambenyaakov]

In fact better on the upper

[@h7qvi]

In the saturated region of a MOSFET, the majority carriers in the channel are near the asymptotic velocity saturation limit IIRC

[@VEC7ORlt]

I'm a bit stumped that desat detection works better at lower gate voltage, but recommended drive is way higher - like +15/-5V, but then again all of it depends on desat voltage threshold. Oh and I've tried this on a MOSFET class D amp I've did for uni degree - worked perfectly.

[@sambenyaakov]

Thanks for sharing. Interesting. I am inclined to think that lower gate voltages are better. All action is around the threshold anyhow and the drop of Vce with higher Vge is not that significant.

[@michaelmorrison7632]

Hello Mr. Sam. I am ina position where I am required to perform a dead short test on the output of an igbt inverter half bridge.. Typically the unit would withstand this rather brutal test, however , recently the igbt's are not able to hold up and violently short in many cases. I am misunderstanding the drive circuit and the term de sat protection. Shouldnt the igbt run in the saturation region always..HELP..

[@sambenyaakov]

Are these the same IGBTs as before? I has a similar problem when replacing IGBTs.

[@michaelmorrison7632]

@@sambenyaakov we have tried three different flavors of igbts. Ironically the one that claims 50 amp seems to hold up better than the 60 amp Period they all have five microsecond Short circuit withstand times I believe we are getting a huge inductive Spike when the short circuit is introduced on the output and I don't think the acpl 3333 J is turning off the gate with the correct profile I don't have my notes in front of me so I'm describing it the best I can I'm trying to convince the powers that be that it might be a good idea to run a bit of conductor from the outputs to the breaker that we are using to introduce the short. It is very frustrating and time-consuming to replace these igbts after each short circuit test otherwise known as a crowbar test

[@sambenyaakov]

@@michaelmorrison7632 I would guess it is the de sat network or the way the short is done and its inductance. .

[@pranit9668]

a fun side quest. try running desat on MOSFET in halfbridge. The waveforms reveal a very interesting phenomenon :)

[@sambenyaakov]

How about a clue?

[@2meters2]

Thank you for this interesting method of over-current protection. A few years ago TI showed a similar method implemented with separate components, but I had not seen this before built-into the driver. I especially like the signal back to the micro controller (schematic at 12:43) which helps in detecting when this over-current situation occurs.

[@sambenyaakov]

👍🙏

[@GeomicroSolution]

Very Nice my friend ❤

[@sambenyaakov]

Thanks

[@angelosgeorgakas1759]

Thank you for this excellent video!

[@sambenyaakov]

Thanks

[@EngineeringEssentials]

👍 great explanation. Thank you sir

[@sambenyaakov]

Thanks

[@DrCyneth]

This was incredibly helpful, thank you

[@biswajit681]

Hi sir many thanks 🙏 could you please make video on multi-Output forward converter and comparison with multi-Output Flyback converter

[@sambenyaakov]

Will try. That's a good topic.

[@electronichome1153]

Excellent lecture! Many thanks!

[@sambenyaakov]

Thanks

[@esijal]

Thanks professor, great presentation 🤞🙏

[@sambenyaakov]

Thanks

[@FurkanKaraçal-i2i]

Thank you

[@sambenyaakov]

Thanks