The FOD2741 Optically Isolated Amplifier consists of the popular KA431 precision programmable shunt reference and an optocoupler. 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.
The document describes the Fairchild FOD2741A, B, and C, which are optically isolated error amplifiers combining a KA431 precision programmable shunt reference with an optocoupler. These devices are designed to reduce component count in AC/DC power supplies and DC/DC converters by integrating the error amplifier, reference voltage, and isolation function into a single 8-pin DIP package.
Key specifications include a 2.5V reference voltage with tolerances of 0.5%, 1%, or 2% depending on the grade (A, B, or C), a Current Transfer Ratio (CTR) ranging from 100% to 200%, and a low temperature coefficient of 50 ppm/°C. The datasheet provides absolute maximum ratings, electrical characteristics such as bandwidth and isolation voltage, typical application circuits, performance curves, and soldering reflow profiles.
| Reference Voltage (FOD2741A) | 0.5% tolerance |
|---|---|
| Reference Voltage (FOD2741B) | 1% tolerance |
| Reference Voltage (FOD2741C) | 2% tolerance |
| Current Transfer Ratio (CTR) | 100% to 200% |
| Temperature Coefficient | 50 ppm/°C max |
| Operating Temperature | -25 to +85 °C |
| Isolation Voltage (Withstand) | 5000 Vrms |
| Bandwidth | 50 kHz |
The device comes in three grades based on reference voltage tolerance: FOD2741A (0.5%), FOD2741B (1%), and FOD2741C (2%).
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.
The device comes in an 8-pin DIP white package.