| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power device that can suppress the instability of an output voltage when a load is light, while reducing a power loss. SOLUTION: The output voltage Vo1 becomes unstable due to the light load LD1, and when the output voltage is higher than a prescribed value 27V exceeding a target value 24V, the potential of a connecting point between a resistor element R1 and a resistor element R2 of a pseudo-load control circuit 4 becomes higher than a contained potential difference between a base and an emitter of a transistor Q2. As a result, the transistor Q2 of a pseudo-load circuit 5 is turned on, and a current flows to a pseudo-load resistor element RB1. When the output voltage Vo1 becomes lower than another prescribed value 21V, the potential of a connecting point between a resistor element R3 and a resistor element R4 of a pseudo-load control circuit 6 becomes lower than a contained potential difference between a base and an emitter of a transistor Q3. As a result, a transistor Q4 of a pseudo-load circuit 8 is turned on, and a current flows to a pseudo-load resistor element RB2. COPYRIGHT: (C)2007,JPO&INPIT
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