4170 Vrms isolation — reinforced barrier for industrial signal isolation
The MOC8106SR2M is a single-channel phototransistor optoisolator from onsemi, offering 4170 Vrms of isolation between the DC input LED and the transistor output. This isolation rating meets the requirements for reinforced insulation per IEC 60950-1, making it suitable for separating low-voltage control circuits from mains-voltage power stages in industrial equipment.
CTR range 50–150% at 10 mA — design margin for logic threshold
This wide spread means the output transistor's collector current can vary by a factor of three across devices. The designer must ensure the downstream logic input sees a valid high or low at both extremes — a pull-up resistor value that works at 150% CTR may not saturate the transistor at 50% CTR. With a maximum Vce saturation of 400 mV at the rated output current, the transistor pulls close to ground when fully on. Switching speed is moderate: typical turn-on time is 2 µs, turn-off is 3 µs, with rise and fall times of 4 µs and 3.5 µs respectively. This limits the practical data rate to about 10 kHz for clean pulse transmission — adequate for status feedback, relay drivers, and low-speed isolated serial links, but not for high-speed communication like SPI or CAN.
Surface-mount 6-SMD gull wing — footprint and temperature range
The part is housed in a 6-SMD gull-wing package (supplier device package 6-SMD), which is a standard wide-body SOIC-6 footprint. The gull-wing leads are solderable with conventional reflow profiles and allow visual inspection of the solder joints. Maximum forward current is 60 mA, so the LED can be pulsed at higher current for faster switching, but continuous operation should stay within the derating curve for the ambient temperature.