| 摘要 |
PROBLEM TO BE SOLVED: To provide an electrostatic discharge protective circuit capable of improving driving capability of an MOS transistor for surge discharge. SOLUTION: In the electrostatic discharge protective circuit, a static electricity detection portion 3 places a first gate control portion 4 in an electrically conductive state when a voltage exceeding an upper-limit voltage Vmax is generated between a power supply terminal 1 and a GND terminal 2 to allow a current to flow from first wiring 11 to a gate of an NMOS transistor 7. Consequently, the gate voltage rises and the NMOS transistor 7 turns on to discharge a surge voltage, so that the voltage of the first wiring 11 drops. When the voltage between the power supply terminal 1 and GND terminal 2 is equal to or lower than the upper-limit voltage Vmax, the first gate control portion 4 is placed in an electrically nonconductive state, so a current is prevented from flowing back from the gate of the NMOS transistor 7 to the first wiring 11 through the first gate control portion 4, thereby preventing the gate voltage of the NMOS transistor 7 from dropping. COPYRIGHT: (C)2011,JPO&INPIT |
