The MOSFET H bridge can work as a good dual motor controller but you
must make shure that there is enough time between switching directions
to prevent overvoltage.  For example, if you are controlling a 12v motor
and switch directions without a time delay the motor will have a 24v
spike accross the coil.  This may not damage the motor immediatly but
over time it will burn out the motor.  Mitubishi makes these two chips
that are dual bi-direction motor controllers and are designed for this
application M54649L and M51714P.  One of the chips has a breaking
function.

Scott
HyperDyne Systems

Jim Ruxton wrote:

> I'm trying to build an N channel MOSFET H bridge to drive a DC motor
> using 2 LT1160 drivers. I am having problems getting it to work
> consistently. Has anyone used these drivers and have you found any
> gotchas that you can relate to me? I've tried varying the Boost
> capacitors and PWM frequency but continue to have problems. Any help
> would be appreciated. Thanks!
> Jim