A method is disclosed for controlling an output impedance of an electronic device of the type having an impedance control terminal to which an external load is to be connected such that a predetermined value of the voltage at the impedance control terminal controls the output impedance of the device. The method is comprised of comparing a reference voltage to a voltage at the impedance control terminal. A variable count signal representing a count value is produced in response to the comparing. The impedance of a variable impedance circuit is varied in response to the count signal, wherein the impedance of the variable impedance circuit controls the voltage at the impedance control terminal. A device connected in parallel with the variable impedance circuit is periodically operated to change (increase/decrease) the impedance of the variable impedance circuit. An apparatus for performing the method is also disclosed.