Power regulating circuit, charging device and power supply mode setting method thereof

A power regulating circuit comprising:

• a detecting module detecting a charge current during a detection time period to obtain a detected value;
• a control module coupled to the detecting module, receiving the detected value, and determining in which one of a trickle charge (TC) range, a constant voltage (CV) range and a constant current (CC) range the detected value locates, wherein values within the TC range are smaller than values within the CV range, and values within the CV range are smaller than values within the CC range;
• and
• an actuating module coupled to the control module and receiving commands from the control module to control the power regulating circuit in a power transmission state or a power off state;
• wherein the control module commands the actuating module in the detection time period to control the power regulating circuit in the power transmission state, adjusts the power regulating circuit to the power off state for a first duration when the detected value is determined as in the TC range by the control module, keeps the power regulating circuit in the power transmission state for a second duration when the detected value is determined as in the CV range by the control module, and keeps the power regulating circuit in the power transmission state for a third duration when the detected value is determined as in the CC range by the control module.