Patent ID: 7498868

Claim:
A constant current circuit for supplying a constant current to a plurality of circuits, each of the plurality of circuits provided to a respective one of a plurality of secondary cells, the plurality of secondary cells connected in series to form an assembled battery, the constant current circuit comprising: a current mirror circuit that includes a plurality of current output transistors each of which is connected to a respective one of the plurality of circuits, the current mirror circuit further including a current input transistor commonly connected to the plurality of current output transistors; and a reference current output circuit connected to the current input transistor of the current mirror circuit and configured to output a reference current to the current input transistor of the current mirror circuit, wherein the plurality of current output transistors has emitters each of which is connected to a voltage line connected to a negative terminal of one of the secondary cells, the plurality of current output transistors further having bases connected to each other, and the current input transistor has an emitter connected to the voltage line and a base connected to the bases of the plurality of current output transistors.