The onsemi H11A4TM is officially classified as Obsolete by the manufacturer. This means onsemi no longer manufactures or sells this part — the only supply channel is independent distribution, where remaining inventory is sourced from surplus, overstock, or end-of-life buybacks. Because the part is obsolete, a last-time-buy window has closed. Any stock available today is from lots produced before the EOL date. Date-code and traceability are confirmed at RFQ — mystery stock surfacing years after the official last-time-buy warrants scrutiny.
7500Vpk isolation — what it means for the BOM
The 7500Vpk isolation rating is the peak voltage the optocoupler can withstand between input and output without breakdown. This is a high-isolation figure, suitable for applications where the primary and secondary circuits must be galvanically separated at elevated voltages — for example, in motor-drive feedback, industrial power supplies, or medical equipment where reinforced insulation is required.
DC input, transistor output — one channel
This is a single-channel optocoupler with a DC input and a phototransistor output with base access. The base pin allows the designer to bias the transistor for faster switching or to use it as a photodiode detector — a flexibility not available in base-less transistor outputs. The minimum current transfer ratio (CTR) is 10% at 10 mA forward current. At 10 mA input, the output transistor can sink at least 1 mA — enough to drive a logic gate or a low-power relay. The typical turn-on and turn-off times are 2 µs each, which limits the switching frequency to roughly 250 kHz before the output waveform degrades. The output transistor is rated for a maximum Vce of 30 V and a saturation voltage of 400 mV at rated current. The forward voltage of the input LED is 1.18 V typical, and the maximum continuous forward current is 60 mA.
6-DIP package — through-hole board integration
The H11A4TM comes in a 6-pin DIP package with 0.400-inch (10.16 mm) body width, through-hole mounting. The supplier device package is listed as 6-DIP. This is the standard DIP-6 footprint, compatible with many existing PCB layouts for optocouplers in this family. The part is supplied in tube packaging, which is typical for through-hole DIP components. No reel or tape options are listed — the tube is the only packaging variant confirmed.