| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a power source circuit using a bipolar transistor suppressing a reactive current when a power source voltage is low, by negatively feedback-controlling the voltage of the emitter collector of an output PNP transistor by first or second deviation amplifiers so as to maintain to be not less than a reference potential difference. SOLUTION: When a power source voltage is boosted, the base current of the output PNP transistor 6 is suppressed through a driving NPN transistor 5 by the negative feedback output of the first deviation amplifier 4 to maintain an output voltage to be a set voltage. In addition, as a potential difference between the power source voltage and the output voltage is not less than the reference potential difference in this range, the second deviation amplifier 9 controls an NPN transistor 31 to be in a disconnected state and the transistor 5 is controlled exclusively by the amplifier 4. Thereby, voltage between an emitter and a collector is negatively feedback-controlled by the amplifier 9 or 4 without regard to the value of the power source voltage and maintained to be not less than the reference potential difference.</p> |
