Voltage selection circuit suitable for use as ESD protection circuit for EEPROM

摘要

A static electrostatic discharge (ESD) protection circuit for the programming voltage line of an electrically erasable programmable read only memory (EEPROM) includes a pair of multiplexors consisting of MOS pass transistors for selecting between the power supply voltage and programmning voltage to be supplied to the EEPROM for its normal and programming modes of operation, respectively. One of the multiplexors performs the voltage selection in accordance with an externally generated differential control signal and a biasing voltage from the second multiplexor. The second multiplexor, in accordance with one of the phases of the differential control signal, automatically selects either the power supply voltage or programming voltage, whichever is larger, for use as the biasing voltage supplied to the first multiplexor.