| 摘要 |
PURPOSE:To drive a current by the minimum power consumption by providing a means for detecting the deepest potential in plural power sources, and an output transistor which is driven by receiving the detected potential of this means by its base. CONSTITUTION:If VCC1 is the highest, the base potential of QB1 in transistors QB1-QBn is the highest, therefore, the transistors QB2-QBn are turned off. The transistor QB1 is turned on, and a current Iref becomes a base current of a transistor Q11. Therefore, the transistor Q11 is turned on, a base current of a transistor Q2 is supplied, and Q2 is driven. When the potential of a power source VCC2 is the highest, a transistor Q12 is turned on in the same way, and the transistor Q2 id driven. Accordingly, a circuit of a system being in the highest potential among the power sources VCC1-VCCn is operated, therefore, the base potential of the transistor Q2 becomes the highest, the emitter potential of the transistor Q2 is raised, and the power consumption in Q2 is reduced.
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