Patent ID: 7663345

Claim:
A DC-DC converter for use in an electronic device that receives an input current and includes a load that operates on the input current and a secondary battery, the DC-DC converter comprising: a control circuit which includes: a first detector which detects whether or not the input current exceeds a first reference value corresponding to a rated supply current to generate a first detection signal; a second detector which detects the difference between a positive charging current for charging the secondary battery and a reference current to generate a second detection signal; a third detector which detects the difference between a charging voltage supplied to the secondary battery and a first reference voltage to generate a third detection signal; a fourth detector which detects whether or not the input current exceeds a second reference value corresponding to the rated supply current to generate a fourth detection signal; and a fifth detector which detects the difference between an output voltage of the DC-DC converter and a second reference voltage to generate a fifth detection signal, wherein the control circuit controls the positive charging current for charging the secondary battery and a negative charging current supplied from the secondary battery to the load based on the first to fifth detection signals.