Abstract: A power supply circuit, an antenna control system, and a digital communication device are provided. The power supply circuit is adapted to supply electronic power to an antenna and includes a power management circuit and a pin. The power management circuit is coupled between a power input terminal and a power output terminal. In a first mode, the pin receives a mode control signal to control the power management circuit to deliver or not deliver electronic power of a power source from the power input terminal to the power output terminal. In a second mode, the pin stops receiving the mode control signal and provides a detection signal, which indicates whether the power supply circuit is overloaded. Thereby, power switching of the antenna and an overload detection/notification function are accomplished by using the single pin.