I am working on a design that requires redundant motor driver circuits. One circuit will be energized (driving a stepper motor with 24V) while the other is not. This second circuit is located on a second circuit board which is not powered. However, both circuits are connected to the motor drive lines (AOUT1, AOUT2, BOUT1, BOUT2). Because of the clamping diodes on these pins of the DRV8711, the motor drive signals from the powered circuit are back-feeding into the power nodes of the unpowered circuit and causing problems. Would it be possible to put a buffer op-amp (or two in parallel) on each of these lines to help isolate them? The op-amps of the unpowered board would be unpowered and therefore not pass the undesired signal to the unpowered DRV8711, but the op-amps on the powered board would virtually invisible as long as the proper part were chosen.
Is this a viable solution?
