Patent ID: 7200764

Claim:
A Personal Digital Assistant, wherein the Personal Digital Assistant outputs a current within a first current range to an external device when supplied with a battery power and outputs a current within a second current range to the external device when supplied with external power through an adapter, comprising: a main device, for performing necessary data processing, enabling a control signal when supplied with external power through the adapter; a switch device comprising a first input terminal receiving battery power, a second input terminal receiving external power, a control terminal receiving the control signal, and an output terminal outputs battery power when the control signal is disabled and outputs external power when the control signal is enabled; and a current limiting device comprising: an impedance device for providing a first impedance and a second impedance, wherein the impedance device outputs the first impedance when the control signal is disabled and outputs the first and the second impedances when the control signal is enabled; and a current limiting module coupled to the output terminal of the switching device, wherein the current limiting module outputs the current within the first current range when receiving the first impedance and outputs the current within the second current range when receiving the first and the second impedances.