Power management circuit and method thereof

摘要

A power management circuit adapted for a portable electronic device is provided. The portable electronic device receives a supply voltage from a USB power supplying port through a built-in USB charging port. The power management circuit includes a USB detection unit, a voltage detection unit, and a control unit. The USB detection unit determines the type of the USB power supplying port. The voltage detection unit detects the supply voltage. The control unit configures the power consumption of the portable electronic device based on the type of the USB power supplying port and the supply voltage. When the portable electronic device initiates booting process with the USB power supplying port being the Dedication Charging Port and the supply voltage being lowered than a threshold, the control unit reduces the power consumption of the portable electronic device to maintain the supply voltage above the threshold for booting stably.

主权项

1. A power management circuit, adapted for a portable electronic device having a universal series bus (USB) charging port, the portable electronic device electrically connected to a USB power supplying port through the USB charging port to receive a supply voltage, the power management circuit comprising:
a USB detection unit, coupled to the USB charging port, determining the type of the USB power supplying port connected to the USB charging port being a Standard Downstream Port (SDP) or a Dedicated Charging Port (DCP); a voltage detection unit, coupled to the USB charging port, detecting the supply voltage; and a control unit, coupled to the USB detection unit and the voltage detection unit, configuring a system power consumption of the portable electronic device based on the type of the USB power supplying port and the supply voltage; wherein when the portable electronic device initiates a booting process with the USB power supplying port being the DCP and the supply voltage being lower than a threshold, the control unit reduces the system power consumption of the portable electronic device maintaining the supply voltage above the threshold for the portable electronic device to initiate the booting process normally; wherein the control unit configures a central processor operating frequency and a brightness level of the portable electronic device to generate multiple power-saving modes; wherein the power-saving modes includes a first power-saving mode and a second power-saving mode, the system power consumption of the portable electronic device in the second power-saving mode being lower than the system power consumption of the portable electronic device in the first power-saving mode, the control unit configuring the central processor operating frequency and the brightness level to respectively generate the first power-saving mode and the second power-saving mode according to the supply power of the USB power supplying port.