| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply driver circuit that produces less power loss, is excellent in the property of response to variation in output, and can be reduced in size. SOLUTION: A driver IC 110 constitutes a switching power supply unit that controls the switching of power transistors Q1 and Q2 that pass a current through a coil L0 by PWM, and outputs a voltage obtained by stepping down/up an input voltage. The driver IC is provided with a transistor Qsg for switching between the inverting input terminal and the non-inverting input terminal of an operational amplifier OP1. While the transistor Q2 is on, the production of potential that becomes undetermined when the transistor Q1 is turned on, that is, when the transistor Q2 is turned off is prevented. The node potential is kept in a state in which the potential is determined. Thus, current detection excellent in response can be implemented. COPYRIGHT: (C)2006,JPO&NCIPI
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