The FOD2742 Optically Isolated Amplifier consists of the popular KA431 precision programmable shunt reference and an optocoupler. The optocoupler is a gallium arsenide (GaAs) light emitting diode optically coupled to a silicon phototransistor. It comes in 3 grades of reference voltage tolerance = 2%, 1%, and 0.5%. The Current Transfer Ratio (CTR) ranges from 100% to 200%. It also has an outstanding temperature coefficient of 50 ppm/°C. It is primarily intended for use as the error amplifier/reference voltage/optocoupler function in isolated ac to dc power supplies and dc/dc converters. When using the FOD2742, power supply designers can reduce the component count and save space in tightly packaged designs. The tight tolerance reference eliminates the need for adjustments in many applications. The device comes in a 8-pin small outline package.
The FOD2742 series combines a precision 2.5 V reference, an optocoupler, and an error amplifier in an 8‑pin SO package. It is offered in three tolerance grades (0.5 %, 1 %, 2 %) and provides a current transfer ratio of 100 % to 200 %.
Typical applications include isolated AC‑DC power supplies and DC‑DC converters. The device features 2,500 V RMS isolation, a low temperature coefficient of 50 ppm/°C, and operates from –25 °C to +85 °C.
| Reference voltage | 2.5 V |
|---|---|
| Current Transfer Ratio (CTR) | 100 % to 200 % |
| Isolation rating | 2,500 V RMS |
| Temperature coefficient | 50 ppm/°C |
| Tolerance (FOD2742A) | 0.5 % |
| Tolerance (FOD2742B) | 1 % |
| Tolerance (FOD2742C) | 2 % |
| Storage temperature range | -40 °C to +125 °C |
| Operating temperature range | -25 °C to +85 °C |
The device provides 2,500 V RMS isolation.
It includes a 2.5 V precision reference.
The reference has a low temperature coefficient of 50 ppm/°C.
FOD2742A is 0.5 %, FOD2742B is 1 %, and FOD2742C is 2 % tolerance.