SECONDARY BATTERY PROTECTION CIRCUIT, BATTERY PACK, BATTERY SYSTEM, AND METHOD FOR PROTECTING SECONDARY BATTERY

A secondary battery protection circuit includes a potential-difference control circuit. The potential-difference control circuit provides, when overcharge is detected by an overcharge detection circuit, a control terminal of a charge control transistor with feedback on a potential-difference detection signal to control a potential difference between an electrode of a secondary battery and a terminal for a load and charger. The potential-difference control circuit provides, when overdischarge is detected by an overdischarge detection circuit, a control terminal of each of the charge control transistor and a discharge control transistor with feedback on the potential-difference detection signal to control the potential difference.