POWER SYSTEM FOR HANDHELD DEVICE

A power system including a battery, a first port, a first converter, a second port, a second converter, a switch, a power controller, and a control unit is provided. The first port is electrically connected to the battery through a first charging/discharging path. The second port is electrically connected to the battery through a second charging/discharging path and is electrically connected to the first port through a third charging/discharging path. The first converter and the second converter are disposed on the first charging/discharging path and the second charging/discharging path respectively. The switch is disposed on the third charging/discharging path. The power controller is electrically connected to the first port and the second port for forming a power transmission mode with an external device. The control unit is configured to control the first converter, the second converter, and the switch according to the power transmission mode.