Charge controller with protective function and battery pack

A charge controller with a protection function, comprising:na charging transistor configured to apply charge current to a secondary battery;a charge control circuit that, when detecting that a charging power supply is connected, controls and causes the charging transistor to apply the charge current;a first control switch element and a second control switch element connected in series between one terminal of the secondary battery and an external terminal; anda protection circuit that, when the secondary battery is over-discharged, turns off the first control switch element to stop discharge current and when the secondary battery is deeply discharged, turns off the second control switch element to prevent the charge current from flowing into the secondary battery,wherein the protection circuit sends a charge inhibit signal to the charge control circuit when the secondary battery is deeply discharged, and while receiving the charge inhibit signal, the charge control circuit keeps the charging transistor off to prevent the charge current from flowing even if detecting that the charging power supply is connected;wherein the charge control circuit is configured to perform constant-current charge control and constant-voltage charge control; andwherein the charge control circuit starts the constant-current charge control upon detecting that the charging power supply is connected while not receiving the charge inhibit signal and switches to the constant-voltage charge control when the voltage of the secondary battery reaches at least a predetermined potential.