Aspects of the disclosure provide an integrated circuit (IC) chip that includes a feedback control circuit and a detecting circuit. The feedback control circuit is configured to govern a feedback signal to a first regulator that regulates a first power supply to the IC chip based on the feedback signal. The feedback control circuit is powered at least partially by a second power supply. The detecting circuit is configured to detect a power down of the second power supply, and to cause the feedback control circuit to be disengaged from the feedback signal in response to the power down.