| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply circuit in which an NMOSNH2 receiving an output voltage produced by stepping down an input voltage is prevented from operating erroneously by an error signal from a control circuit. SOLUTION: The power supply circuit comprises a first N type MOSFET having a drain being applied with an input voltage, a second N type MOSFET connected in series with the first N type MOSFET, a third N type MOSFET having a source connected with the source of the first N type MOSFET through a coil and a drain delivering the output voltage, a circuit for controlling the first and second N type MOSFETs to perform switching operation and for turning the third N type MOSFET on to obtain an output voltage produced by stepping down an input voltage, and a state setting circuit for turning the third N type MOSFET on independently of the control circuit. COPYRIGHT: (C)2006,JPO&NCIPI
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