AN INTEGRATED SRAM AND FLOTOX EEPROM MEMORY DEVICE

摘要

A nonvolatile SRAM circuit has an SRAM cell and one or two FLOTOX EEPROM cells connected to the data storage terminals of the SRAM cell. In programming to a first data level, the threshold voltage of a FLOTOX EEPROM transistor is brought to a programmed voltage level greater than a read voltage level and erasing to a second data level, the threshold voltage of the FLOTOX EEPROM transistor is brought to an erased voltage level less than the read voltage level. The nonvolatile SRAM array provides for restoring data to an SRAM cell from a FLOTOX EEPROM memory cell(s) at a power initiation and storing data to the FLOTOX EEPROM memory cell(s) to the SRAM cell at power termination. A power detection circuit for providing signals indicating power initiation and power termination to instigate restoration and storing of data between an SRAM cell and a FLOTOX EEPROM cell(s).