The LT2940 is a power and current monitor suitable for 4V to 80V systems. The LT2940 measures a high side current and a differential voltage, multiplies them and outputs a current proportional to instantaneous power with ±5% accuracy. Bidirectional high side currents and bipolar voltage differences up to 80V are correctly handled by the four-quadrant multiplier and push-pull output stages, which allows the LT2940 to indicate forward and reverse power flow. An auxiliary comparator with inverting and noninverting open-collector outputs makes the LT2940 a complete power level monitor. In addition, an output current proportional to the sensed high side current allows current monitoring. The current mode outputs make scaling, filtering and integration as simple as selecting an external resistor and/or capacitor.