The MOC8106SR2VM: The 4170Vrms isolation rating qualifies this opto for reinforced insulation in mains-referenced circuits — think AC-DC power supplies, motor-drive feedback, and PLC digital inputs where the primary side sees line voltage and the secondary side is human-accessible low-voltage logic.
CTR tolerance — the margin that decides your pull-up
The current transfer ratio spans 50% to 150% at If=10mA — a 3:1 spread. That means at the minimum CTR, 10mA input yields only 5mA output drive; at maximum CTR, the same input gives 15mA. The pull-up resistor must be sized so that even at 50% CTR the output voltage at the collector drops below the logic threshold, while at 150% CTR the output transistor does not saturate so hard that turn-off time stretches. Turn-on and turn-off times are 2µs and 3µs typical, with rise/fall of 4µs/3.5µs max — adequate for 10-100 kHz switching signals but not for high-speed data. The 60mA absolute-max forward current means the LED can be driven from a 24V PLC output through a 390-ohm resistor without exceeding the limit.
Package and board-fit note
Housed in a 6-SMD Gull Wing package (supplier device package 6-SMD), the lead pitch and body dimensions match the standard SOIC-6 footprint used across the onsemi optocoupler family. The gull-wing leads provide a visible solder joint for AOI inspection and relieve mechanical strain between the PCB and the molded body.