Optoisolator Question

Okay, so I already know this is a stupid question, but I want to double check.

I want to control a N-Channel using a FPGA. VDS of the mosfet will be connected to a 15 V 9AH battery. To control the mosfet, I was thinking about using this optoisolator http://www.vishay.com/docs/81314/vo3120.pdf. to turn on/off the gate of the mosfet. I'm assuming it's not safe to connect VCC and VEE of the optoisolator to my battery because of the high current? If so, then what voltage regulator could I get can handle the high current rating.

Sorry for the stupid question, but I do not want to burn any components during this.

michaelkellett over 11 years ago

It's the voltage rating that matters - the opto-isolator is Ok to connect to the 15V battery as long as you are sure that the voltage across VCC-VEE will never exceed 32V. (You need to check that this won't happen if the charger is connected and the battery suddenly disconnected.)
You need to limit the input current with a suitable series resistor.

MK
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Former Member over 11 years ago in reply to michaelkellett

Okay! So choosing the series resistance for VCC is simply V/I? (15/I_desired)? I'm looking in the datasheet for the voltage drop of the transistors inside the optoisolator.
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