Boostrap capacitor sizing

Thread Starter

SiCEngineer

Joined May 22, 2019
258
Hi All,

Does the capacitor within a high-side driver have to discharge completely to be effective? I have a high-side driver in my application and noticed that the capacitor discharges from about 15V to about 13V only, each switching action. What occurs if the boot strap capacitor is too big like in this case? I have been getting current shoot-through in my FET's when my controller starts to make adjustments. Could it be because of the oversized bootstrap capacitor or should I look elsewhere?
 

OBW0549

Joined Mar 2, 2015
3,566
Ideally, a bootstrap capacitor shouldn't discharge at all, and within reasonable limits the larger the capacitor the better. If yours is discharging from 15V to 13V, I'd say that sounds about right. As for your shoot-through current, I'd look elsewhere for the cause.
 
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