Patent ID: 8395359

Claim:
A charge controller comprising: a power supply circuit having an input terminal thereof connected to an input voltage and an output terminal thereof connected to a load, which converts the input voltage into an output voltage for supply to the load at the output terminal, the power supply circuit including: an output current detection circuit to detect an output current supplied through the power supply circuit; and an output current limiting circuit to limit the output current below a maximum output current limit; and a battery charge circuit having an input terminal thereof connected to the output terminal of the power supply circuit and an output terminal thereof connected to a secondary battery, which derives power from the power supply circuit to charge the secondary battery, the battery charge circuit including: a charge current detection circuit to detect a charge current supplied to the secondary battery; and a charge current setting circuit connected to the output current detection circuit and the charge current detection circuit to regulate the charge current to a set current value determined based on the detected output current and the detected charge current as given by: I<Ilim+I 2 −I 1 wherein “I” represents the set current value, “Ilim” representing a control parameter, “I 1 ” represents the detected output current, and “I 2 ” represents the detected charge current.