Built-in current sensor for I.sub.DDQ testing

摘要

A current sensor (10), for sensing a quiescent current (I.sub. DDQ) drawn by an integrated circuit (12) from a supply voltage V.sub.DD includes a current sink and voltage transducer (14) for sinking current from the integrated circuit during a logic transition and for providing a voltage indicative of the quiescent current when the circuit operates in its quiescent state. A comparator (18) compares this voltage to a reference voltage representative of a prescribed quiescent current. The comparator is coupled to a preamplifier stage (38) which serves to generate an indicating voltage in accordance with the comparator output signal. The indicating voltage from the preamplifier stage is stabilized by a stabilizing circuit (58) against variations in the supply voltage V. sub.DD to assure that the indicating voltage provides an accurate measure of whether the quiescent current I.sub.DDQ is above or below a prescribed current.