Hi Kevin,
[quote user="Kevin Chen58"]1. We shorted one of the DRV8803 outputs to 24V，and the short current is about 9.5A. This current flow into ground and cause ground voltage level rise up, the amplitude is exceed 1V. Is this will cause the driver logic go wrong？[/quote]
By wrong, do you mean temporarily or permanently? When ground rises, it can cause the digital logic to interpret signals incorrectly. This should be a short term event. If the inputs are being set to 0V and do not follow the ground rising, this could violate the absolute minimums on the digital inputs and result in permanent damage.
[quote user="Kevin Chen58"] 2. In HTSSOP package, pin 5 and pin 12 are connected inside of DRV8803，But they are not connected with PPAD。Can we regard pin 5&12 as logic ground of DRV8803？[/quote]
No, the pins labelled gnd are the ground pins for all circuits of the device.