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UCC21732: Overcurrent and Short Circuit Protection Based on Desaturation Circuit

Biruk Damitie
Prodigy 200 points
Part Number: UCC21732

Tool/software:

Hello Experts,

In the UCC21732 gate driver data sheet, the overcurrent voltage threshold is 0.7V, so my question is: is this 0.7 current voltage threshold fixed for all kinds of voltage loads and currents at the load side?
I have a design spec of 400Vdc and 200A. My MOSFET can support 40A. I did not know how I could relate my practical parameters and application to the UCC21732 driver specification, like overcurrent and short circuit protection based on desaturation conditions.

How can I choose the value of R1, R2, R3, and Cblk ?

Kindly provide insights on the above points

Best
Biruk

 

  • +1
    TI__Expert 6730 points

    Hello Biruk, 

    Check out the UCC217XX Excel calculator linked here. If you're using the OC-as-DESAT approach, first, determine at what Vds threshold the device is considered overcurrent. You might want to test this parameter across temperature. Then, determine what's the longest blanking time and shutdown time that can be well tolerated in the system and not cause device damage. Usually SiC FETs can tolerate ~2-3us between DESAT and shutdown. 

    After you have a good estimation of the above needed parameters, adjust the resistor and Cblk size in the Excel calculator, and it will output the Vds detection threshold and blanking time. Adjust in the final system as needed. 

    Thanks! 

    Vivian