Help Driving FET under given restraints.

Discussion in 'The Projects Forum' started by danielb33, Oct 4, 2012.

  1. danielb33

    Thread Starter Member

    Aug 20, 2012
    I have a buck/boost converter with input 5-40VDC in and steady 12VDC out. This is powering 2 STDT relays to control motor drive. Fets are controlling the relay on/off cycle. FETs are driven by an STM32F1 mircro, which have push/pull PWM outputs for driving. The problem is these output a steady 3.3V, but my board needs to power from .2mA to 30-35Amps. I can't seem to find a FET that I can drive with this low of a voltage without dissipating 4 Watts or so through the small internal variable resistance at high currents. This WOULD be solved if I knew of a way to correctly drive the FET through a higher voltage from my board, say the output of the buck boost for instance. I am not very experienced with design, all I know is that my FET needs to be driven "correctly" or it will not operated my PWM correctly. Does anyone know how to gain my 3.3V output to a higher voltage output while maintaining proper FET drive?