| 摘要 |
PROBLEM TO BE SOLVED: To provide an electrostatic protective circuit for protecting a buffer MOSFET while preventing a current from concentrating on the buffer MOSFET and eliminating wasteful power consumption when static electricity is discharged after detecting an electrostatic surge. SOLUTION: The electrostatic protective circuit is provided with first/second power supply terminals 110, 112, an input/output terminal 111 for external connection, a buffer PMOSFET 108 for pulling up the input/output to high-level potential, a buffer NMOSFET 107 for pulling down the input/output to low-level potential, a rectifier cell 109 connected between the first/second power supply terminals, and a detector 101 for detecting the electrostatic surge by comparing potential between the input/output terminal and the first power supply terminal. When the electrostatic surge is detected by the detector, the buffer NMOSFET is turned off while controlling the gate potential of the buffer NMOSFET 107. Surge discharging is executed by parasitic bipolar transistors of the NMOSFETs 107, 119. COPYRIGHT: (C)2007,JPO&INPIT
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