| 摘要 |
PURPOSE:To increase the lifetime of a dry battery by supplying a driving current of a switching circuit and a driving current of a constant-voltage circuit for stabilizing the output voltage from a constant-current source. CONSTITUTION:When an input voltage VIN is lowered, an output voltage VOUT tends to become constant, and an input current will thereby increase. Thus, the collector current of a transistor Q11 is increased, the emitter current of a transistor Q12 will thus increase, and the base current Ib will increase. However, since a current Io which flows through a constant-current source 21 is constant, a zener current Iz will decrease when the base current Ib thus increases, and the operating point of a constant-voltage diode D13 is further displaced from the constant-voltage operating range. As a result, the output voltage VOUT becomes not constant and gradually becomes lower. In this manner, the lifetime of the dry battery can be increased. |
