H-Bridge Woes

Thread Starter


Joined 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.


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?