Protection against inverted polarity for integrated electronic circuits in CMOS-technology

摘要

A polarity-reversal protection device for integrated circuits, comprising a substrate of a first conductivity type; a well region of a second conductivity type opposite said first conductivity type, within said substrate; a field effect transistor having drain and source regions within said well of said first conductivity type, said drain region being connectable to external circuitry to be protected from polarity reversal of a supply voltage, said supply voltage being applied to said source region via a low impedance; and resistor means, coupled to said well region, for enabling said supply voltage to be applied therethrough to said well region, said resistor means operative to sink current during undesirable polarity reversal of the supply voltage, thereby preventing damage to the external circuitry and to the FET itself.