A power management system includes a direct current-direct current DC-DC conversion circuit, a first control circuit, a charging circuit, an input port, and an output port. The input port is configured to receive an input voltage. The output port is configured to supply an output voltage to a load. The DC-DC conversion circuit is configured to charge the output port from the input port, to adjust the output voltage. The first control circuit is configured to: obtain a second feedback voltage of the output voltage from the output port, generate a first control signal based on the second feedback voltage and a second reference signal, and supply the first control signal to the charging circuit. The charging circuit charges the output port from the input port based on the first control signal, to supplementally adjust the output voltage.