onsemi has marked the H11A8173SD as Obsolete. For existing BOM lines, this part is sourced through independent distribution channels — quantities are lot-specific and confirmed at RFQ.
Isolation and CTR — the fit parameters that matter
Rated for 5300Vrms isolation — this is a reinforced-level isolation barrier for galvanic separation between a DC input side and a transistor output side. The 50% to 600% Current Transfer Ratio range at 5mA forward current means the output transistor saturates reliably across a wide LED drive tolerance, which simplifies the bias resistor selection on the input. The output transistor handles up to 70V collector-emitter and 50mA continuous current, with a 200mV Vce(sat) max — low enough to keep dissipation under 10mW at typical logic-level loads. Rise and fall times are 2.4µs typical, which suits 10-100kHz switching in PLC input modules, motor drive feedback, or isolated serial interfaces. Operating temperature spans -55°C to +100°C — the full industrial range. At the cold end, the CTR typically drops; at 100°C, the leakage current rises. The 50% min CTR at 5mA provides headroom for this drift.
Surface-mount package — board-fit note
Supplied in a 4-SMD Gull Wing package, surface-mount, on Tape & Reel. The Gull Wing leads provide a visible solder joint for AOI inspection. The 4-SMD footprint is shared across the H11A series — a common land pattern that also accepts the DIP-4 through-hole variant on the same PCB if a rework substitution is needed.