Hello All,

Long time lurker first time poster. I am working on a simple MOSFET isolated gate driver. The FETs will be used allow or stop the charge and discharge of a battery pack (I will add the back to back FETs later, I recognize that right now it will only prevent charging do to the body diode). I already have these 12V to 15V isolated power supplies that I want to use. I could connect them directly to the gate, but the issues is that the power supply voltage ramps up and down relatively slowly and that could have the FETs operating outside of their SOA in some fault conditions. My thought was to use a Zener diode and an optocoupler to only allow voltage to start flowing once the voltage of the DCDC is above 13V. Does this seem like a reasonable approach? I cant help but think there is a simpler solution.

Any feedback would be greatly appreciated.

Thanks!

P.S. Im using high side FETs for reasons

 

How slowly is that "Relatively slowly", in volts per minute, or is it minutes per volt??? The question is what are you dealing with, really??

 

R-10 will slow things down much more than the start-up-delay of the Module.
It should be replaced with an Inductor as per the Data-Sheet instructions.

A Current-Regulator would be much better than a Zener-Diode.
That would also eliminate R-11.

Do not switch the Input of the Isolated-Supply.
The Isolated Supply should be powered at all times, and only it's Output switched.
It's Output should charge a Capacitor through the above mentioned Inductor,
the capacitor should probably be around ~10X the combined Capacitance of the combined FET-Gates,
then switch the Capacitor to charge-up the FET-Gates with substantial Current for fast switching times.

How much Current are You Switching ?
What are You switching and why ?
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