ISO5452: SIC short circuit protection

Hermann Sundklakk

Part Number: ISO5452

I'm developing a motor controller using the ISO5452 as the gatedriver controling a SIC mosfet with a Ron of 0.03 ohm

I'm looking into how to decrease the current that the gatedriver shuts down on, the circuit looks like this:

diode with Vf of 1.3-2 V in series with a resistor R, following the design suggestion in the datasheet

To avoid a redesign I need a solution which either adds a diode with larger forward voltage or increases the resistor value R

I'm looking for a solution where the gate driver shuts down at approx 80 A, giving the following calculation

(9V- Vf-80*Ron)/500uA = [8900 10300] ohm for R

Is this calculation correct, can I just increase the resistor R or is there another way to achieve the short circuit protection?

over 5 years ago

0 Don Dapkus over 5 years ago

TI__Guru**** 189399 points

Hi Hermann,

Thanks for your post. We will help you get the correct trip level for your application.

Did you see section 10.2.2.8 DESAT Diode and DESAT Threshold in the d/s that discusses how to tune the short-circuit trip point? I think this should help you design your desired level.

0 Hermann Sundklakk over 5 years ago in reply to Don Dapkus

Prodigy 40 points

Hi
I did have a look at 10.2.2.8 and this other question: e2e.ti.com/.../695843

From this I based the calculations in my first question, the question is whether you agree with my approach and that I can increase the resistance for achieving a lower current threshold?

Hermann

0 Xiong Li over 5 years ago in reply to Hermann Sundklakk

TI__Intellectual 1665 points

Hi Hermann,

Your calculation looks correct. Based on the calculation, the resistance is around 10k which can work but leave less margin for noise immunity. A better alternative would be to add a Zener diode in series with the DESAT diode.

With Regards,

Xiong

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ISO5452: SIC short circuit protection