Besides zero-crossing and non-zero crossing, key performance parameters include trigger current, static dv/dt (d-v-d-t) and blocking voltage. Trigger current is the input current required to switch on the photo sensitive TRIAC. Low currents allow direct control by a microcontroller. Note that the trigger current increases with operating temperature so it must be set for the maximum operating temperature allowing for a safety margin and up to 30% degradation of the infrared emitting diode over the lifetime of the part. Static dv/dt defines the rate of change of the voltage that the output can withstand in the off state without triggering. Noisy environments, like factory floors, require dv/dt’s of 5 or 10 kV/µs (kilovolt per microsecond). Consumer applications can get by with 1.5 kV/µs or less. Finally, blocking voltage is the level of voltage the output can withstand without triggering on.