Circuit and operating method for integrated interface of PDA and wireless communication system

A battery charging method for a device that comprises a PDA, a wireless communication system, and a power system having a battery and is charged via an external charging cable, the device further having an external charging circuit for charging the battery, and the wireless communication system having an internal charging circuit for charging the battery, the charging method comprising:

• performing current charging to the battery via the external charging circuit by using the external charging cable;
• turning on the wireless communication system;
• turning on the internal charging circuit for performing constant-voltage charging to the battery after the wireless communication system is turned on;
• and
• performing constant-voltage charging to the battery via the internal charging circuit when a battery potential achieves a first predetermined value.