Adaptive Fail-Save Power-On Control Circuit

摘要

A circuit includes an input for receiving power from an external power supply, a voltage regulator coupled to the power input and providing regulated voltage to an external circuit and to the power supply control circuit itself, and a first switch coupled between ground and an Enable input of the voltage regulator. A control input of the first switch is coupled to the regulated voltage, such that when the voltage regulator provides regulated voltage, the first switch is closed, coupling the Enable input to ground, keeping the voltage regulator active. A first switching circuit provides manual activation and deactivation of the voltage regulator; a second switching circuit provides automatic activation of the voltage regulator whenever the power input becomes powered. An intervening circuit prevents the second switching circuit from activating the voltage regulator when the first switching circuit has deactivated it, despite the continued presence of the external power supply.

主权项

1. A power supply control circuit comprising:
a power input for receiving power from an external power supply; a voltage regulator coupled to the power input and providing regulated voltage to an external circuit and to the power supply control circuit itself; a first, normally-open, electrically-operated, switch coupled between ground and an active-low Enable input of the voltage regulator, a control input of the first switch coupled to the regulated voltage, such that when the voltage regulator provides the regulated voltage, the first switch is closed, coupling the Enable input of the voltage regulator to ground, keeping the voltage regulator active; a first power switching circuit providing manual activation and deactivation of the voltage regulator; a second power switching circuit providing automatic activation of the voltage regulator whenever the power input becomes powered; and an intervening circuit preventing the second power switching circuit from activating the voltage regulator when the first power switching circuit has deactivated the voltage regulator, despite the continued presence of power from the external power supply on the power input.