Startup circuit for self-supplied voltage regulator

摘要

A startup circuit for starting up a self-supplied voltage regulator which initiates startup by applying a voltage from a voltage supply to the startup circuit thus causing a voltage at an output node to rise. This rise will start the operation of the differential amplifier of the voltage regulator. When the voltage at the output node has reached the desired final output voltage, the startup circuit disconnects from the voltage regulator. The criterion for switching off the startup circuit is determined by a comparator which compares the output current capability of the voltage regulator with its output current plus the startup current. Inputs to the differential amplifier, such as the reference voltage, derive their power from the output node.