Design FAQ: Safety and regulatory issues for optocouplers

What is the difference between an isolation withstand voltage and working voltage for an optocoupler? The UL1577 rating of 3750Vrms per minute or 5000Vrms per minute means that devices can survive and isolate transient (1min) voltage spikes with these values. This is a momentary insulation withstand rating for one minute. The input-output momentary withstand voltage rating should not be interpreted as continuous voltage that can be applied across the optocoupler insulation barrier.