7500Vpk isolation in a surface-mount phototransistor coupler
The onsemi H11A5SM is a single-channel optoisolator in a 6-SMD gull-wing package, pairing a DC-input LED with a phototransistor output that includes a base terminal for external bias or feedback control. Its 7500Vpk isolation rating suits applications requiring reinforced galvanic separation between control and load circuits, such as AC mains monitoring, motor-drive feedback, and industrial PLC I/O isolation where the primary-side transient exceeds standard 5000V ratings.
Signal-transfer parametrics for the BOM line
Minimum current transfer ratio of 30% at 10 mA forward current ensures the output transistor can drive a logic-level load with reasonable LED drive budget — a 10 mA input yields at least 3 mA collector current, enough to pull a 5V CMOS input low through a 1.5 kΩ pull-up. Typical turn-on and turn-off times of 2 µs each set the switching ceiling below 250 kHz; this part is sized for 50/60 Hz line-sync and low-speed digital isolation, not high-frequency data paths. Output side rated to 30V collector-emitter with 400 mV max saturation — the low Vce(sat) keeps power dissipation down when switching a relay coil or a DC load near the 30V ceiling.