Charge control circuit

A charge control circuit for supplying power from an external power source to a first common node and charging a second common node from the first common node, a regulator circuit being coupled between the external power source and the first common node, and a transistor being coupled between the first common node and the second common node, the charge control circuit comprising:

• a current sensing and control device, for sensing a current from the first common node to the second common node and generating a first control signal, wherein the first control signal is not transmitted to a gate of the transistor to control the transistor but is sent to the regulator circuit;
• a first voltage sensing and control device, for sensing a voltage at the first common node and generating a conduction control signal to decide a conduction status of the transistor, wherein the gate of the transistor receives the conduction control signal but does not receive the first control signal;
• and
• a second voltage sensing and control device, for sensing a voltage at the second common node and generating a second control signal which is sent to the regulator circuit;
• wherein the regulator circuit provides system power to the first common node according to the first control signal and the second control signal.