Hello, we have a GD system which controls up to 9 devices, all with a 100kHz 15V ac supply - all isolated ( 1500VDC working ) - which is converted to +15 & -5V on the GD boards, opto isolated GD signals, allowing a 0% & 100% on time ( i.e. indefinite ON time) all with >10kV/uS common mode, and propagation delay of 100nS max for ON command and 80nS max for OFF command. Ron and Roff selectable by user - desat detect fed back via opto coupler on each GD board ( open ckt would look like a desat ) allowing for overall controller to count de-sats and either turn whole system off at first de-sat - or count de-sats and stop system at some count number ...