The HiZ Problem of Power Management IC Testing

A well-known source of trouble during iddq or digital testing in production is the so-called HiZ-problem. Pattern generation tools set the ATE drivers connected to digital I or I/O DUT pins which are not supposed to have any influence on the test result to high-impedance. Thus the state of these pins during testing is not clearly defined which often leads to correlation issues. A similar problem exists for DC input pins of power management devices which are left undefined during testing. This paper explains the issues and a methodology to avoid them.