mosfet driver for pwm controlled h bridge

Discussion in 'General Electronics Chat' started by dmta, Mar 24, 2013.

  1. dmta

    Thread Starter Member

    Mar 24, 2013
    Hi all,

    I am making an H bridge for a supply voltage range of 12V to 24V and a max current of 4A. The motor speed will be controlled by a pwm signal (>10kHz) provided by a PIC microcontroller.

    I noticed that for driving the gate people use gate drivers (because the gate has some capacitance and it needing more than 5V to fully switch on).

    I searched on the internet and came across “boot strap” circuits and so on but did not understand how they operated. Can I use something like a comparator to do this or can someone please provide me with a suitable gate driving circuit.

  2. shortbus

    AAC Fanatic!

    Sep 30, 2009
    You have not given the part number for the mosfet so it is hard to answer this. But gate drivers are the way to go. They will take your PIC out put and by supplying what ever voltage Vgs the mosfet needs. Vgs is the number in the data sheet for the mosfet, that you are using to look for. It is shown on the first page of a data sheet, do not use the thresh hold voltage- Vgs(th) on the second page. That is the shut off point of a mosfet.

    In a H-bridge you want the mosfets turned fully on, that is what the Vgs number does.
    dmta likes this.
  3. dmta

    Thread Starter Member

    Mar 24, 2013
    Thank you verymuch shortbus, it was very useful information (specially about Vgs-th).