An overcurrent protection circuit of a rechargeable battery, comprising:
- a current detection terminal at which a voltage converted from a discharge current of the rechargeable battery is detected;
- and
- an overcurrent return resistor connecting part that connects said current detection terminal to overcurrent detection resistors having different resistances in accordance with a level of the voltage detected at said current detection terminal when the voltage detected at said current detection terminal is equal to or greater than a discharge overcurrent detection voltage and a discharge overcurrent state in which an overcurrent flows from said rechargeable battery is detected,
- wherein said overcurrent return resistor connecting part includes:
- the first overcurrent return resistor and the second overcurrent return resistor parallel to each other and connected to said current detection terminal;
- and
- a switching part configured to switch between a parallel connection state where said first overcurrent return resistor and said second overcurrent return resistor are connected in parallel and a single connection state where said second overcurrent return resistor is solely connected to said current detection terminal,
- wherein said switching part includes:
- a first switching element serially connected to said first overcurrent return resistor in a first branch circuit containing said first overcurrent return resistor;
- a second switching element serially connected to said second overcurrent return resistor in a second branch circuit containing said second overcurrent return resistor;
- and
- a logic operation part configured to turn on said first switching element and said second switching element when the voltage at said current detection terminal is equal to or smaller than a predetermined threshold voltage, and turn on said first switching element and turn off said second switching element when the voltage at said current detection terminal is greater than said predetermined threshold voltage.