Patent ID: 8289000

Claim:
A charge control circuit that includes a non-insulated step-down switching regulator using an inductor and charges a secondary battery connected to an output terminal using a voltage input to an input terminal as a power supply, the charge control circuit comprising: a switching element that performs a switching operation in accordance with an input control signal and charges the inductor with the input voltage; a rectification element that discharges the inductor; a current detection circuit part that generates a proportional current proportional to a current flowing to the switching element and generates and outputs a current sense voltage corresponding to the proportional current; and a control circuit part that performs PWM control for constant voltage output operations with respect to the switching element in accordance with a current mode control method using the current sense voltage at the time of constant voltage charging in which a constant voltage is supplied to the secondary battery for charging, and performs PWM control for constant current output operations with respect to the switching element at the time of constant current charging in which a constant current is supplied to the secondary battery for charging; wherein the control circuit part compares the current sense voltage with a fourth reference voltage generated by adding a difference voltage between a second predetermined reference voltage and the current sense voltage to the second reference voltage, and performs the PWM control for the constant current output operations using a pulse signal indicating a comparison result.