| 摘要 |
PURPOSE:To improve surge breakdown withstanding voltage, by connecting a drain and a gate to an output terminal, and setting the threshold voltage of a surge absorbing MOS transistor, whose source is connected to one power source, larger than the range of an open drain output voltage. CONSTITUTION:The drain and the gate of a surge absorbing MOS transistor 28 are connected to the drain of an MOS transistor 15. The source of the MOS transistor 28 is connected to a Vss power source terminal 14. A threshold voltage Vth of the surge absorbing MOS transistor 28 is set at a value higher than the voltage range of an open drain output at the time of operation. Since the threshold voltage of the surge absorbing MOS transistor 28 is higher than the range of the open drain output voltage, the transistor 28 is not operated at the time of normal operation. The protecting operation is performed only when surge is inputted. |
