The onsemi H11A3S is officially obsolete. No successor part number is recorded — the H11A family remains the legacy reference for through-hole and SMD optoisolators with similar pinouts.
5300Vrms isolation — the fit driver
Rated for 5300Vrms galvanic isolation between input and output, this part suits applications requiring reinforced insulation per IEC 60950-1 or equivalent — think industrial PSU feedback, PLC digital input isolation, or motor-drive signal separation. The DC input drives a phototransistor with base access — the base pin allows external bias adjustment or bandwidth shaping, useful when the downstream circuit needs faster turn-off than the 2 µs typ the internal phototransistor alone provides. Minimum current transfer ratio of 20% at 10 mA forward current means the output transistor conducts at least 2 mA when the LED is driven at 10 mA — enough to saturate a TTL or CMOS input with a 10 kΩ pull-up. The 400 mV max Vce(sat) keeps the logic-low voltage within the 0.8 V threshold of most 5 V logic families.
SMD gull-wing — board-fit note
Supplied in a 6-SMD gull-wing package on tube. The 1.27 mm (0.050-inch) lead pitch matches standard SOIC-6 footprints — reflow-compatible, no special stencil aperture needed. Operating temperature range -55°C to 100°C covers industrial and most automotive under-hood environments.