| 摘要 |
PURPOSE:To use an IC pin as an external capacitive pin of a constant voltage source as well as a switch control pin by providing a switch provided with a resistance between a ripple eliminating capacitive pin and the earth in a push- pull constant voltage circuit of IC type. CONSTITUTION:A switch 43 and a resistance 44 are connected between an IC pin 32, which is provided for a ripple eliminating capacity 33 of the constant voltage circuit, and the earth. When the switch 43 is switched to connect the resistance 44 to the IC pin 32, a switching transistor TR22 in the IC is made conductive. When the resistance 44 is removed from the IC pin 32, the TR22 is made non-conductive. Thus, the IC pin 32 is used as the ripple eliminating capacitive pin and the control pin of the switch in the IC. |
