Originally Posted by jglenn
I don't think a little brush noise will result in voltage excursions that exceed the max ratings of the fets, if derated properly.
Have you ever connected a scope to a motor and measured the voltage excursions? Even the cheapest toys have caps across the motor leads and if anyone would cut corners they would.
Boot strap circuits are basically charge pumps and need to be pulsing to work. The schematic might work if the charge pump of IC1 was connected to Q4 and IC2's charge pump was connected to Q2. Also at WOT the charge pumps still need to be pulsed so the FETs cannot be turned on in a static manner for long times. Depending on how large C4 and C5 are they could maintain a voltage for several minutes but eventually there will be smoke.