AC/DC input optoisolator for universal line sensing
The onsemi H11AA4SR2M is a single-channel optoisolator that accepts both AC and DC input drive, making it suitable for line-voltage zero-crossing detection, AC mains monitoring, and universal-input signal isolation where the polarity is not fixed. Rated for 4170Vrms isolation between input and output, it provides a reinforced safety barrier for applications requiring galvanic separation up to that voltage class. The output is a phototransistor with the base terminal brought out, allowing the designer to bias the base for faster switching or to implement feedback around the optocoupler.
Key parametrics for BOM fit and design margin
Minimum current transfer ratio of 100% at 10 mA forward current ensures the output transistor saturates reliably when driving logic inputs or low-power loads up to 50 mA continuous. Maximum Vce saturation of 400 mV at rated output current keeps the voltage drop low in the on-state, preserving headroom for downstream circuitry.
Housed in a 6-SMD Gull Wing package, the H11AA4SR2M is designed for surface-mount assembly on standard PCB footprints. The supplier device package is 6-SMD, matching the case outline.
ROHS3 compliant, so it meets the latest EU restriction-of-hazardous-substances directive for lead-free assembly.