| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply circuit capable of preventing a system reset, a fault and the like, of a microcomputer, etc. which receive source voltage supply. SOLUTION: An assist circuit 30c of a power supply circuit 30 outputs a value obtained by amplifying an error between a voltage Va detected based on a drive voltage Vcc of a drive voltage line +Vcc and a reference voltage Vr by an operational amplifier OP 32 as a control voltage Vp and a reference voltage Vp'+, and a comparator CP 33 outputs a comparison result voltage Vd when an output difference is generated between both the voltages based on the control voltage Vp and the reference voltage Vp'+. By this, even if the output difference is generated between the control voltage Vp and the reference voltage Vp'+ due to delayed transition in phase compensation circuits (C22, Q24), a comparison result voltage Vd is outputted from the comparator CP33, and a transistor Q 34 pulls the control voltage Vp into the direction of the potential Vt of the microcomputer MC 5 in an operation state. Thus, the drop of the drive voltage Vcc is restrained, and the system reset of the microcomputer MC 5 is prevented. COPYRIGHT: (C)2007,JPO&INPIT
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