The TIL5942 and TIL5942A consist of an advanced current-mode-PWM controller and a TL1431 adjustable precision shunt regulator, incorporated in a single package. The controller provides a photodetector, an improved MOSFET drive output, and an LED for isolation. The TL1431 is configured as a precision reference/error amplifier. Using the TIL5942 or the TIL5942A, the power-supply designer can implement the controller for an isolated dc/dc converter or off-line switching power supply, with one IC and a few passive components. The TIL5942 standard version has a reference voltage tolerance of 0.8% and the TIL5942A has a reference voltage tolerance of 0.4% These controllers are available in a 16-pin PDIP with a lead form for through-hole, or gull-wing lead form for surface-mount applications. These devices operate over a 40C to 100C junction temperature range. End equipment applications for the TIL5942 and the TIL5942A include isolated ac-to-dc power supplies and dc/dc converters.