I need to add some short circuit protection to my mosfet h-bridge. Is it acceptable to simply trigger a transistor which ties the gate pins of the lower side of the h-bridge to ground (the transistor can be triggered when the voltage across a low value resistor exceeds a certain value)? I've tested it and it works, just dont want anything to get damaged if it's used often.
Are you trying to protect your h-bridge against excessive current drawn by the motor, or as a bandaid because your h-bridge driver turns on the top side devices before turning off the bottom side devices?
The best thing is to inhibit the short circuits. If your H-Bridge is succeptible to shorts due error in the uC software, then it (H-Bridge) needs to be redesigned for more robustness/confiability.