ISO5852S: Problem with soft turn off

3rd_n_Long

Part Number: ISO5852S

We are initiating a desat condition, but the ISO5852 does not seem to be turning off softly. I've attached a portion of the schematic below. Sorry for the poor sizing.

over 6 years ago

0 Xiong Li over 6 years ago

TI__Intellectual 1665 points

Hi,

Could you please capture the gate voltage waveform with and without DESAT triggering?

Also, the value of C24 is 1nF which may be too small. Could you please change it to 10nF or higher and have a shot?

With Regards,

Xiong

0 Rais Miftakhutdinov over 6 years ago in reply to Xiong Li

TI__Prodigy 335 points

Also, what kind of load is used for Vgs measurements? Is it real power device or capacitance of some value? Regards, Rais

0 Rais Miftakhutdinov over 6 years ago in reply to Rais Miftakhutdinov

TI__Prodigy 335 points

I also suggest to connect R34 directly to pin 6 OutL instead of connecting to R28.
Currently, 100 ohm R28 in C24 discharge path reduces significantly impact of increased driver's output impedance during soft shutdown.
Effectivness of soft shutdown will be greatly improved by connecting directly to pin 6. It will also be less dependent on gate resistors.
Regards, Rais

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ISO5852S: Problem with soft turn off