Help me design a circuit for MOSFET driver

Hi,

I want to design a buck converter Vin = 70v, Vout = 12v, Iout = 8A,

I have done all the calculations for capacitor, inductor , MOSFET and diode. Now I am having problem in designing the circuit for the MOSFET Driver.

How can I drive the MOSFET, are there any circuit out there, how PIC's PWM can help me?

any example circuits will be great help, thanks in advance

Buck converter

Hello,

I assume that you want to use an N-channel mosfet (as these are better then P-channel).

The drive for the N-channel mosfet must be about 8…10V above the power supply and has to go to below 2V, so your driver need a voltage range of about 80V.

I don't know your hardware knowledge. When limited, you can use a "high side" driver chip that contains the bootstrap power supply and level shifter so that you can drive that chip with you PIC directly. When you search for "high side driver" you will get ideas when you want to design the driver yourself.

You may use a half bridge driver with another mosfet that shorts the diode (synchronous rectifier) during the conduction phase. This enhances the efficiency.

Did you also simulate/calculate the stability of the PWM loop, over current protection and transient behavior. Designing a good buck regulator from the ground up takes more time the expected.