The FOD2742 is a Fairchild Semiconductor Corporation's optically isolated error amplifier. It combines the KA431 precision programmable shunt reference and an optocoupler. The product has a 2.5V reference, CTR 100% to 200%, 2500V RMS isolation, UL, BSI, VDE, CSA approvals, low temperature coefficient 50 ppm/°C maximum, 0.5%, 1% and 2% tolerance. It is mainly used for isolated ac to dc power supplies and dc/dc converters error amplifier/reference voltage/optocoupler function.
The FOD2742A/B/C devices combine a precision 2.5 V reference, an optocoupler and an error‑amplifier in an 8‑pin SO package. They are intended for isolated AC‑DC power supplies and DC‑DC converters, offering tight reference tolerances (0.5 %‑2 %) and a low temperature coefficient of 50 ppm/°C.
Key electrical parameters include a current transfer ratio of 100 %‑200 %, 2.5 kV rms isolation, and operating temperature range from –25 °C to +85 °C. The datasheet provides absolute maximum ratings, pin definitions, and typical performance curves for design reference.
| Reference voltage | 2.5 V |
|---|---|
| Current Transfer Ratio (CTR) | 100 %‑200 % |
| Isolation rating | 2,500 V rms |
| Temperature coefficient | 50 ppm/°C |
| Storage temperature range | -40 °C to +125 °C |
| Operating temperature range | -25 °C to +85 °C |
| Collector‑Emitter breakdown voltage | 70 V |
Each device provides a 2.5 V precision reference.
The devices are rated for 2,500 V rms isolation.
The reference has a low temperature coefficient of 50 ppm/°C.
The CTR ranges from 100 % to 200 %.