UCC21732-Q1: UCC21732-Q1

Igor Volkov

Part Number: UCC21732-Q1

Good day!How to choose a resistor value "Rdesat" for mode Overcurrent Based on Desaturation Circuit. The calculation of the resistor "Rdesat" is not given in the datasheet? Can i choose 0 ohm value for resistor "Rdesat"? Thank you.

over 4 years ago

0 Audrey Dearien7 over 4 years ago

TI__Expert 4875 points

Hello Igor,

The series resistor R_DESAT is used to limit current during forward voltage transients due to the IGBT switching. We recommend using a resistance between 100 Ohms to 1 kOhms.

Also, please take a look at our Fundamentals of Drivers Guide which discusses design of DESAT circuitry.

Regards,

Audrey

0 Igor Volkov over 4 years ago in reply to Audrey Dearien7

Prodigy 60 points

rdesat affects "Vdet", therefore the formula should contain rdsat.I guess the formula should be like this

where

rdesat-resistance "Rdesat"

Vfdiode-forward voltage diode "Dhv"

Idesat-current through "Rdesat"

Vocht- is the detection threshold voltage of the gate driver

Is it correct? or ihave to use formula from datasheet

0 Audrey Dearien7 over 4 years ago in reply to Igor Volkov

TI__Expert 4875 points

Hi Igor,

That is correct. To account for Rdesat, please use the equation as you have attached.

Regards,

Audrey

Power management

Power management forum

UCC21732-Q1: UCC21732-Q1