An integrated circuit includes an output circuit having a first terminal adapted to couple to an external power supply, a second terminal adapted to couple to a reference potential, and a third, control terminal. The first and second terminals of the output circuit provide output terminals of the integrated circuit. The integrated circuit further includes an impedance measurement circuit responsive to the external power supply to generate a control signal for coupling to the control terminal of the output circuit. The control signal controls a current level associated with the output circuit. A corresponding method is also described.