FOD2741B

Overview

The FOD2741B is a single-channel optically isolated error amplifier manufactured by Fairchild Semiconductor. It integrates a precision programmable shunt reference with an NPN phototransistor output optocoupler in an 8-pin DIP package. The device provides high isolation voltage of 5000 Vrms and operates within a temperature range of -25°C to +85°C. Key electrical parameters include a nominal current transfer ratio of 100%, a maximum collector-emitter saturation voltage of 400 mV, and a maximum forward current of 20 mA.

Feature Summary

• Integrates a precision programmable shunt reference with an optocoupler for compact error amplification
• Provides high-voltage electrical isolation between input and output circuits
• Features low collector-emitter saturation voltage for efficient signal transmission

Applications

• Switching power supply feedback loops
• Isolated voltage regulation circuits
• Error amplification in isolated DC-DC converters

Procurement Notes

Verify the manufacturer origin as Fairchild Semiconductor or onsemi, noting that onsemi acquired Fairchild's semiconductor business. Confirm the package type is PDIP-8 and check for RoHS compliance status. Ensure the part number suffix matches the specific variant required, as availability may vary due to lifecycle status changes. Cross-reference datasheets from both original Fairchild and current onsemi sources for accurate specifications.

Selection Notes

Select this component when a combined error amplifier and isolation stage is needed in a single package. It is suitable for applications requiring precise voltage referencing with galvanic isolation. Consider the operating temperature range and insulation voltage requirements relative to the system design. Verify compatibility with existing PCB footprints for 8-pin DIP packages.

Part Context

The FOD2741B belongs to the FOD2741 series of optically isolated amplifiers. This series is designed to simplify the design of isolated feedback paths in power electronics. The integration of the shunt reference reduces component count compared to discrete solutions. The device is widely used in industrial and consumer power supplies where isolation safety standards are critical.

Replacement Considerations

Check for direct pin-compatible substitutes from onsemi or other manufacturers offering similar integrated error amplifier optocouplers. Verify that replacement parts maintain the same isolation voltage rating and current transfer characteristics. Ensure thermal performance and package dimensions match the existing design constraints.