H-Bridge Woes

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

  1. barrymead

    Thread Starter New Member

    May 3, 2009
    1
    0
    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
    charging.

    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
    262
    11
    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
    5,072
    6
    How stable is your VCC under load?
     
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