Low dropout regulators with fast response speed for mode switching

摘要

A low dropout regulator is provided. The low dropout regulator includes an output-stage circuit, a reference-voltage generation circuit, a timing controller, and an active low dropout circuit. When the low dropout regulator is at an operation mode, the output-stage circuit is controlled by a first enable signal to generate first output voltage to an output node of the low dropout regulator. The reference-voltage generation circuit is controlled by a bias voltage to generate a first reference voltage. The timing controller is coupled to the output node and receives the first reference voltage. When the low dropout regulator is in the operation mode, the timing controller programs the first enable signal according to the reference voltage and the voltage at the output node. When the low dropout regulator is in a standby mode, the active low dropout circuit generates a second output voltage to the output node.