A high side current monitor circuit includes an op amp which is coupled across a sensing element which carries a current I sense and develops a shunt voltage V sense . A feedback transistor driven by the op amp output conducts an output current I out through a resistor to a current output node necessary to make the op amp inputs equal, such that I out is proportional to I sense . I out is conducted through a resistor to generate a ground-referred voltage proportional to V sense . When the common mode voltage of V sense is greater than the op amp's breakdown voltage, a discrete transistor is connected between the current output node and ground to stand off the voltage across the amp. The monitor circuit is arranged such that it can be powered with a limited fraction of the common mode voltage when used with a discrete transistor, and is self-biased when used without a discrete transistor.