The H11B1M is a single-channel optoisolator from onsemi with a Darlington transistor output that includes a base terminal — this gives you the option to tailor the switching threshold with an external resistor, something a standard Darlington opto lacks. Its 4170 Vrms isolation rating covers industrial motor drives, PLC I/O modules, and medical equipment where galvanic isolation between control and power domains is non-negotiable. The 500% minimum current transfer ratio at just 1 mA forward current means the LED side draws very little from the microcontroller GPIO — a 3.3 V logic output can drive it directly through a series resistor, saving a transistor stage.
Switching speed and saturation voltage — timing and drive margin
Turn-on time is 25 µs typical, turn-off 18 µs typical — this is not a high-speed isolator; it suits 10 kHz and below switching, relay drivers, and DC signal detection where the 25 µs delay is well within the system timing budget. Vce saturation is 1 V maximum at the rated output current, which keeps the Darlington drop low enough to drive a 5 V relay coil or a 24 V PLC input without exceeding the 30 V output maximum. The 150 mA continuous output current per channel is enough for small solenoids, indicator LEDs, or logic-level shifters — but for loads above 100 mA, check the thermal derating in the 6-DIP package.
Active production, through-hole package — sourcing posture
This is a production part you can commit to a BOM without obsolescence risk.