ISO5852SDWR: functions of the Zener diode (parallel with C_{desat}) in protection circuit

Hisui Yan

The question is about a design in the application note "tiduc70a: IGBT Gate Driver Reference Design for Parallel IGBTs With Short-Circuit Protection and External BJT Buffer". In the Fig. 9 of the article, a Zener diode (D3 in red circle) is connected in parallel with the C_{desat} (C3). Could anyone tell me the function of the Zener diode? Is it just for protection from some high voltage?

over 5 years ago

0 Jeffrey Mueller over 5 years ago

TI__Genius 12990 points

Hi Hisui,

Thanks for your question on ISO5852, The engineer supporting this device is out of the office at the moment. He will be back Monday and can respond then.

thanks,

0 Aishwarya Bhatnagar over 5 years ago

TI__Intellectual 1730 points

Hi Hisui Yan,
The diode D3 is used for protecting the DESAT pin from overvoltage.

0 Hisui Yan over 5 years ago in reply to Aishwarya Bhatnagar

Prodigy 180 points

Thanks for your answer.
So could you tell me when the DESET pin could suffer from overvoltage? Since the parasitic capacitance of D1 and D2 is much smaller than C3, it looks that the voltage of DESAT will be limited.

0 Aishwarya Bhatnagar over 5 years ago in reply to Hisui Yan

TI__Intellectual 1730 points

Hello Hisui Yan,

If you are using diodes with lower parasitic capacitances, the zener diode will not be needed.

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ISO5852SDWR: functions of the Zener diode (parallel with C_{desat}) in protection circuit