| 摘要 |
PROBLEM TO BE SOLVED: To provide a power unit which has a DC-DC converter where a switching element is built in a semiconductor integrated circuit and automatically judges whether the constitution thereof is a step-up type or a step-down type and further prevents miss connection. SOLUTION: This DC-DC converter is composed of a DC voltage source VCC, switching elements SW1 and SW2 in a semiconductor integrated circuit 1, a coil L1, and an output capacitor Co. The judging circuit 2 of the semiconductor integrated circuit 1 judges whether the DC-DC converter is a step-up type or a step-down type, based on the voltage level of a terminal V2, and judges a judgement signal. A control circuit part 4 controls and drives the switching elements SW1 and SW2 so that the DC-DC converter may operate as a step-up converter or a step-down converter, based on the voltage of a feedback terminal FB and the judgement signal from the judging circuit 2. By this constitution, it automatically judges the DC converter which is constituted as a step-up type or a step-down type, thereby being controlling it properly. COPYRIGHT: (C)2009,JPO&INPIT
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