| 摘要 |
PURPOSE:To maintain charge current constant by connecting/disconnecting a FET, connected in series with a rechargeable battery and performing PWM control, through a transistor based on the voltage variation of a current detecting resistor caused by the variation of charge current. CONSTITUTION:A FET performing PWM control is connected with an object to be recharged, i.e. an NiCd battery. A current detecting resistor (r) is connected through the slider of a potentiometer PM to the base of a transistor Q. Collector of the transistor Q is connected with the gate of the FET. When excessive current flows through the NiCd battery, voltage across the resistor (r) increases to increase the voltage of the slider in the potentiometer PM thus turning the transistor Q ON, bringing the FET closely to OFF state and reducing the charge current. When the charge current is reduced below a predetermined level, PWM control is resumed. By such arrangement, the battery can be recharged with overcurrent being blocked. |
