H-Bridge Woes

Discussion in 'The Projects Forum' started by barrymead, May 3, 2009.

  1. barrymead

    Thread Starter New Member

    May 3, 2009
    I have been trying for over 1 week to get an ALL N-CHANNEL FET h-bridge working.
    I have tried the MC33883 chip and the HIP4082 chip, and neither seem to work as advertised.

    I built the circuits exactly like the examples shown in the application notes, and they do
    not seem to work. I am trying to drive large MOSFET's the IRFS3004-7PPbF, which
    has a gate capacitance of 9130 pf.

    I have scaled up the charge pump capacitors accordingly, yet nothing seems to work.

    I either get no gate drive, or wildly oscillating gate drive at about 1.6Khz.
    I have read hundreds of pages of application notes, and dozens of group postings, and many people are having trouble getting these things to work.

    I even wen to the trouble of making sure that the pulse width modulator input
    to the low side drivers is always running, because some of the h-bridge controller chips
    don't have a full charge pump included within them, and rely on the operation of the
    low size driver PWM current pulses to keep the high side gate driver capacitors

    I have provided everything I can think of that these chips think they want to operate
    properly, and they still will not work.
  2. Darren Holdstock

    Active Member

    Feb 10, 2009
    You're running a big load by the looks of the big output transistors and small value/high wattage current sense resistor. What is the load, and are you using the real load for your tests?
  3. thingmaker3

    Retired Moderator

    May 16, 2005
    How stable is your VCC under load?