VARIABLE OUTPUT VOLTAGE REGULATOR

PROBLEM TO BE SOLVED: To provide a variable output voltage regulator capable of controlling a regulator IC without being affected by noise and holding supply power voltage to a device within a fixed range. SOLUTION: An output voltage value Vout of a linear regulator IC 21 is divided by feedback circuit resistances R1 and R2 to feedback a voltage value Vfb to the linear regulator IC 21, and a voltage control part 30 is connected between both ends of the feedback circuit resistance R2. The voltage control part 30 includes MOS FETs 31 and 32, an adjusting resistance element R3 and a voltage monitoring circuit 33, and a series circuit of the MOS FET 31 and the adjusting resistance element R3 is connected to the feedback circuit resistance R2 in parallel. The voltage monitoring circuit 33 is arranged in the vicinity of a device to monitor supply voltage to the device, the MOS FETs 32 and 31 are subjected to on/off control in accordance with a monitored voltage value Vdet, and the adjusting resistance element R3 is connected separately from or in parallel with the feedback circuit resistance R2 to adjust the output voltage Vout of the linear regulator IC 21. COPYRIGHT: (C)2010,JPO&INPIT