| 摘要 |
PROBLEM TO BE SOLVED: To provide a voltage control circuit capable of outputting a constant direct current voltage regardless of a variation in input voltage and load current by a simple circuit constitution. SOLUTION: To a series circuit comprising a resistor 5, NPN 6, 7, and a resistor 8 connected in series between a node N1 and grounding potential GND, a PMOS13 is connected in parallel thereto and the conduction state of the PMOS13 is controlled by the potential of a node N2. Since the potential of the node N2 is determined by a current I0 flowing in the series circuit, when the current I0 is increased, the on-resistance of the PMOS13 is made smaller, and when the I0 current is decreased, the on-resistance of the PMOS13 is controlled to be made larger. This suppresses the variation in the current I0 flowing in the series circuit, and regardless of the variation in input voltage VI, a value of the current I0 of the series circuit is held approximately constant, and a constant voltage VO can be outputted. COPYRIGHT: (C)2009,JPO&INPIT
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