hi , am working on a dc dc buck converter . the switch am using is a mosfet IRF740. and i have designed a gate driver with an optocoupler for the mosfet ,because my pwm source is 3v.
but the gate driver circuit works fine /with a vcc =10/ and the dc dc converter circuit also works fine without being connected to the gate driver .but when i connect them the , it doesnot drive the mosfet .plz help me i cannot find any other fault .

 

Hello,

I moved your post to a more suitable place.

Can you post the schematics of what you have upto now?

Bertus

 

hi , am working on a dc dc buck converter . the switch am using is a mosfet IRF740. and i have designed a gate driver with an optocoupler for the mosfet ,because my pwm source is 3v.
but the gate driver circuit works fine /with a vcc =10/ and the dc dc converter circuit also works fine without being connected to the gate driver .but when i connect them the , it doesnot drive the mosfet .plz help me i cannot find any other fault .

The IRF740 is not a logic-level MOSFET. You must get Vgs to 10v before the MOSFET is fully turned on.

I do not know why you are using a high-voltage MOSFET with such a low voltage. It is a poor choice for the job.