| 摘要 |
PROBLEM TO BE SOLVED: To provide a drive circuit for driving a load by performing switching control of an input DC voltage depending on an output DC voltage thereby creating a predetermined output DC voltage in which an output voltage not higher than an input voltage can be applied to the load. SOLUTION: The drive circuit for driving a load (LED) by converting a load current flowing through the load (LED) into a voltage and controlling an input DC voltage (VDD) such that a constant load current flows through the load (LED) based on the converted voltage (VFB) comprises a means (121) for creating reference voltages (Vref10, Vref20), an error amplifier (22) for detecting the error between the converted voltage (VFB) and the reference voltages (Vref10, Vref20) created by the reference voltage creating means (121), and control means (23, 24, L, SBD) for driving the load (LED) by stepping up the input DC voltage (VDD) such that the load current becomes constant based on the output signal from the error amplifier (22) wherein the reference voltage creating means (121) can select a predetermined reference voltage from the plurality of reference voltages (Vref10, Vref20). COPYRIGHT: (C)2006,JPO&NCIPI
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