Non-bootstrap PMOS/NMOS half-bridge mosfet driver

Discussion in 'General Electronics Chat' started by bobstay, Feb 9, 2011.

  1. bobstay

    Thread Starter New Member

    Jan 21, 2011
    Hi all,

    First-time poster here, please be gentle :rolleyes: I'm looking for a device which I suspect has gone out of fashion.

    I want to build a synchronous-rectifier DC-DC switcher which can go to 100% duty cycle (DC). I will need a gate driver chip for the mosfets, as I want to use quite a high PWM frequency. I can find all sorts of bootstrap-style gate drivers designed for using two N-channel fets, which use a capacitor to boost the gate voltage for the high-side N-channel fet. They also have an integrated dead-time generator to prevent shoot-through currents. But, I understand these won't work for me as they can't go to 100% duty cycle because they require some switching to recharge their bootstrap capacitor.

    I therefore intend to use a P-channel high-side fet and an N-channel low-side fet. So, I want to find a gate driver chip that has the following characteristics:

    - Dual gate driver for PMOS high-side and NMOS low-side half-bridge
    - (This means both outputs are in-phase, barring dead-time generation)
    - Single TTL PWM input
    - Automatic dead-time generation
    - Will allow me to go to 100% duty cycle with the high-side fet permanently on and the low-side fet permanently off

    I've searched high and low on my favourite component suppliers' sites and semiconductor manufacturers' sites, without success. They have dozens of varieties of bootstrap-style devices for driving dual NMOS half-bridges, but none for PMOS/NMOS. Does anyone know if such a beast exists?
  2. Brafferton

    New Member

    Feb 9, 2011