Multi-function voltage regulator

A multi-function voltage regulator for both DCDC function and LDO function includes a first transistor, a second transistor and a voltage control unit. The first transistor has a first terminal and a second terminal respectively connected to a first node and a second node. The second transistor has a first terminal and a second terminal respectively connected to the first node and a third node (voltage output node). The voltage control unit has a first output terminal and a second output terminal for respectively controlling actions of the first transistor and the second transistor so that an output voltage of the third node is a default voltage. The voltage control unit further has a first input terminal, a second input terminal and a ground terminal respectively connected to the second node, the third node and a ground node. The voltage control unit utilizes a voltage of the second node as a mode selection signal to select the DCDC function or LDO function.