Greetings:
I am nearing completion of a PWM amplifier design based on the Apex SA60. It will be a highly flexible platform capable of being configured for voltage PWM amplification mode, voltage-to-current PWM amplification mode, and voltage amplification with average current mode control.
The power amp will contain it's own 4W DC-DC converter to generate local signal processing supply voltage +-15V. That freed me from concerns about ground loops resulting from having one low voltage supply, 2 high power supplies, and 4 PWM amps all tied together. So, there will be basically two banks of 2 PWM amps, each supplied by its own high power supply.
The signal input to the PWM amp PCB is via a LT1167 instrument amp. Thus, it is differential. The inputs are protected by 5k resistors, and have 1M resistors to the PWM amp's local ground.
Here's the potential problem: what bad might happen if I leave the PWM amp's power system totally floating with respect to the chassis (earth) ground? The reason I would want to do this is because of short circuit protection. I have the ability to current limit via the current mode control if the differential H-bridge output is shorted. However, is one leg or another of the bridge is shorted to the PWM amp's local power ground, then BANG!
Can I simply expose the differential input to the outside world of a completely floating power system without trouble?
Thanks for input.
Good day!