Charging device capable of dynamically adjusting charging power

A charging device capable of dynamically adjusting a charging power within a system block of a portable system, wherein the system block consists of the charging device and a main function device, and an external power source is coupled to the system block for supplying a work current to the main function device and for charging a rechargeable battery in the charging device, the charging device comprising:

• a DC-DC converter power stage coupled to the external power source for supplying a charging current to the rechargeable battery;
• a current error amplifier, coupled to the DC-DC converter power stage for setting a charging current adjustment signal according to a charging current signal and a charge current operation signal, and the charging current adjustment signal being fed to the DC-DC converter power stage for adjusting the charging current;
• a first current detecting device, coupled to the DC-DC converter power stage, current error amplifier and the rechargeable battery, for outputting the charging current signal based upon the charging current, and the charging current being fed to the rechargeable battery to charge the rechargeable battery;
• and
• a current detecting/comparating device, coupled to the external power source and the current error amplifier, for outputting the charge current operation signal based upon the work current and a calculated charge current signal.