PROTECTION CIRCUIT

摘要

As a protection circuit for protecting a battery pack from an excess current and an excess voltage by using a protection element wherein a heating element and a fuse element are provided on a board, and a detecting means, a protection circuit which can be manufactured at low cost is provided by using a common protection element, irrespective of current rating and voltage rating of the battery pack. A protection circuit (1A) protects a battery pack (5), in which secondary batteries (6) are connected in series, from an excess current and an excess voltage. The protection circuit (1A) is provided with a protection element (2A) wherein a heating element (3) and a fuse element (4) are provided on a board; and a detecting means (7), which detects an excess voltage between discretionary batteries in the battery pack (5) and switches a current flowing in the heating element (3). In the protection circuit (1A), the current flowing in the heating element (3) is switched on by the detecting means (7) when the excess voltage is detected, and the voltages of the prescribed number of batteries connected in series in the battery pack (5) are applied to the heating element (3). Then, the heating element (3) generates heat, and the fuse element (4) melts down.