| 摘要 |
PURPOSE:To use a plurality of input protective resistors at a number of times by connecting each one end of a plurality of the input protective resistors to the input terminals of the input protective device for a MOS type integrated circuit and connecting the other ends to grounding potential points through several diode. CONSTITUTION:The input protective resistors R1, R2, R3 are all constituted similarly, and the formula of R1>R2>R3 is set. A polysilicon layer 13 formed into an insulating layer 12 formed onto a semiconductor substrate 11 is used as a resistor. Electric wiring 14, 15 are extracted from both end sections of the polysilicon layer 13, and formed by aluminum, etc. When positive polarity surge voltage is applied to an input terminal In, maximum currents flow through the resistor R3, thus resulting in the breakdown of the diode D3. Even when the resistor R3 is fused at that time, the device can be used even by surge voltage twice in total because the two resistors R1, R2 remain. The number of resistors R can be increased. |
