H11A4300 — obsolete optoisolator with 5300Vrms isolation
The onsemi H11A4300 is a single-channel optoisolator in a 6-DIP through-hole package, providing 5300Vrms galvanic isolation between a DC input LED and a phototransistor output with a base terminal.
Parametric profile and signal-chain fit
Minimum current transfer ratio is 10% at 10 mA forward current — the output transistor needs at least that much collector current relative to the LED drive to guarantee logic-level switching at the load side. Typical turn-on and turn-off times are 2 µs each, making the H11A4300 suitable for isolating digital signals up to roughly 250 kHz without pulse-width distortion. Forward voltage is 1.18 V typical at rated current, and the LED can handle up to 100 mA continuous DC forward current — enough margin for high-drive applications or derating over temperature. Maximum output voltage is 30 V, limiting the collector supply to low-voltage logic or small relay coils — not suitable for 48 V or higher bus voltages. Operating temperature range of -55°C to 100°C covers industrial and some automotive under-hood environments, though the part lacks AEC-Q qualification.
No pin-compatible direct replacement is listed by the manufacturer.