| 摘要 |
PROBLEM TO BE SOLVED: To obtain a constant voltage circuit capable of surely preventing the generation of a large rush current and suppressing the occurrence of an overshoot in an output voltage. SOLUTION: When a starting signal CE is changed from a low level to a high level, an error amplifier circuit 3 and an operation amplifier circuit 4 are activated, a switch SW1 is simultaneously turned on to be in a conductive state, a switch SW2 is turned off to be in an interrupted state, a capacitor C1 is charged by a constant current i1 from a constant current source 5, and a lamp voltage VA increases at a constant inclination. Although an output voltage Vout also starts to be raised because the error amplifier circuit 3 starts to be operated, when the output voltage Vout exceeds the lamp voltage VA, an output voltage of the operation amplifier circuit 4 is raised to raise a gate voltage of an output transistor M1, raising the impedance of the output transistor M1, thus lowering the output voltage Vout. COPYRIGHT: (C)2009,JPO&INPIT
|
