Patent ID: 8179156

Claim:
A voltage regulator having a component test circuit comprsing: the voltage regulator configured to receive an input voltage and form an output current to charge an output capacitor in order to form an output voltage on an output of the voltage regulator, the voltage regulator having a normal operating mode and a open loop operating mode; an error amplifier coupled to receive a feedback voltage that is representative of the output voltage and form an error signal on an output of the error amplifier, the voltage regulator configured to regulate the output voltage responsively to the feedback voltage during the normal operating mode; a current control circuit configured to receive the error signal from the error amplifier and store a value of the error signal during the normal operating mode, the current control circuit configured to form an output signal that is representative of the stored value of the error signal during the open loop operating mode; an output circuit configured to receive the output signal from the current control circuit during the open loop operating mode and form the output current to be representative of the output signal; a first circuit configured to receive the output voltage and detect a.c. signals on d.c. value of the output voltage, the first circuit configured to form a first control signal indicating detection of the a.c. signals; and a logic circuit coupled to receive the first control signal and to use the first control signal to assert a second control signal and set the operating mode of the voltage regulator to the open loop operating mode, the logic circuit configured to use the first control signal to detect a component failure and responsively assert a third control signal after detecting the component failure.