Gain Degradation Over Time
Over time the gain on the OC100HG will decrease as rapidly as 30% over a three-hour time frame when running both LEDs at the full rated current of 100mA. Lower operating levels of LED current results in a slower decline in opto-coupler gain, but a gain drop has been observed in even very low LED current levels over time.

Solution
VMI suggests using the OC100G opto-coupler as a replacement. Gain in the OC100G is less severe over time, but the initial gain is less than that of the OC100HG.

If long-term gain stability is necessary in your application, we recommend the OC100G.