| 摘要 |
PURPOSE:To make the titled device suitable for circuit integration by supplying the current sum of currents from a 1st current switch and a 2nd current switch having an opposite switching polarity to the 1st current switch to a base of the 1st transistor (TR) to make the TRs into the off-state and the saturated state with simple constitution independently of power fluctuation. CONSTITUTION:With the 1st current switch 1 turned on, a current mirror circuit comprising TRs 3, 4 cannot provide a current from a collector of the TR 4, then the TR 4 is saturated and the base potential of a TR 7 reaches a value being a subtraction of a saturated potential Vsat(4) of the TR 4 from a potential VCC of a power terminal 20. On the other hand, with the 1st current switch 1 turned off, since the TR 4 is turned off, the base potential of the TR 7 reaches a value being the subtraction of a base-emitter voltage VBE(7) of the TR 7 from the potential VCC of the power supply 20. Thus, a high resistor and a reference potential source having been employed conventionally are eliminated from the 2nd current switch 18 and a constant current source 18.
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