An apparatus embodiment includes a voltage regulator circuit that provides a regulated voltage supply signal, logic state circuitry, test control circuitry, and a supply-signal monitoring circuit. The logic state circuitry includes logic modules that are reconfigured between application controlled self-test modes in which data is shifted through the logic module and while being powered from the regulated voltage supply signal. The test control circuitry operates the controlled self-test mode by causing a predetermined set of the data to shift through the logic modules and that causes the logic state circuitry to load the voltage regulator circuit by stressing the voltage regulator circuit. The supply-signal monitoring circuit monitors a quality parameter of the regulated voltage supply signal and provides an indication of characteristics of the regulated voltage supply signal which bear on a likelihood that the voltage regulator circuit is associated with defective circuitry.