The monolithic integrated circuit contains all the necessary monitoring functions to control the output of a complex power system. Overvoltage (OV) sensing is provided to trigger an external SCR to "skid" shutdown, an undervoltage (UV) circuit can be used to monitor output or sample voltages at the input; and a third op amp/comparator is available for current sensing (CL ) all contained in this IC, plus an independent, accurate reference generator. Overvoltage and undervoltage detection circuits can be programmed externally for minimum fault duration before triggering. All functions contain open collectors that can be used independently or wired together, and although the outputs are only overvoltage detection circuits, it is directly connected to the SCR trigger which can selectively activate any other output, or from an external signal. The OV circuit also includes an optional latch and external reset function. The UC1544/2544/3544 devices add versatility and are completely uncommitted to enable each stage to monitor input voltages less than 2.5V by dividing the sensed voltage by the internal reference voltage. Current sensing can use an external compensation circuit for linear amplifiers or as a highgain comparator. Although nominally a zero offset input, a fixed threshold may be added with an external resistor. Instead of the current limit, this circuit may also be used as an additional voltage monitor. The internal reference voltage generator circuit is trimmed, eliminating the need for external power either from the potentiometer and the entire circuit can be monitored directly from the output or from a separate bias voltage.