The TPS5904 and TPS5904A optoisolated feedback amplifiers consist of a precision programmable reference and an optocoupler. Reference-voltage tolerance for the TPS5904 is 0.8%, and for the TPS5904A is 0.5%. These devices are primarily intended for use as the error-amplifier/reference/isolation-amplifier element in isolated ac-to-dc power supplies and dc/dc converters. The optocoupler is a gallium-arsenide (GaAs) light-emitting diode that emits at a wavelength of 940 nm, combined with a silicon phototransistor. The current transfer ratio (CTR) ranges from 100% to 400% in the standard version. The TPS5904A version with a 150%-to-300% CTR is available for higher-performance applications. When using the TPS5904 or TPS5904A, power supply designers can reduce component count and save space in tightly packaged designs. The tight-tolerance reference eliminates the need for adjustments in many applications. The TPS5904 and TPS5904A are characterized for operation from 40C to 100C and each device is supplied in an 8-pin DIP or in an 8-pin gull-wing surface-mount package (DCS).