| 摘要 |
PROBLEM TO BE SOLVED: To suppress marked increase in power loss at heavy load by stabilizing a value of a power supply voltage at light loading, without the need for preparing a three-terminal regulator or the like, with respect to the value of the power supply voltage rise. SOLUTION: In a power feed control part 23 with a voltage limit function, when a voltage Vo1 exceeds a fixed value, a current amount flowing to a switching element Q11 inserted into a line of the voltage Vo1 in series is limited, according to the rising amount of the voltage, and controls the voltage Vo1 so as to be stabilized within a constant range. In this constitution, limiting operation of the current amount will not be generated in a state where the voltage Vo1 is not higher than a fixed value at heavy load. In addition, normally, the switching element Q11 is arranged, in order to turn on/off the supply of the voltage Vo1 according to the turning-on/off of a main power supply. COPYRIGHT: (C)2008,JPO&INPIT
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