| 摘要 |
PURPOSE:To decrease number of terminals without incurring the increase in current consumption and complicated circuit constitution by adding an external switch to a constant voltage source terminal and using the changeover control of the external switch so as to switch the operating state and nonoperating state of the constant voltage source circuit. CONSTITUTION:A bias capacitor (C) 14 is mounted externally between a power terminal 11 and ground, a capacitor C15 is mounted externally between a constant voltage source 12 and ground and an externally mounted switch 21 is connected to the terminal 12. The ground terminal 13 is connected to ground. Emitters of PNP transistors (TR)Q1, Q2, collectors of NPN TRQ3 and collectors of NPN TRs Q5, Q6 are connected to the terminal 11. The constant voltage generating circuit 16 is connected between the collector of the TRQ2 and the terminal 13, and a load 17 is connected between the terminals 12 and 13. In connecting the switch 21 to the ground side, the TRQ4 is turned off to inactivate the constant current source circuit 23 and in throwing the switch 21 to the power supply, the TRQ4 is turned on to activate the circuit 23. Thus, number of terminals of the constant voltage source circuit is reduced.
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