A 32-bit RISC microcontroller with 448K bytes of embedded flash memory

This paper describes a sub-half micron embedded flash EEPROM developed for high speed microcontroller applications. A 32-bit RISC microcontroller with 448 kbytes (3.67 Mbits) of embedded flash EEPROM is presented. High density flash memory is achieved by utilizing a single transistor NOR type cell that employs Fowler-Nordheim electron tunneling for both program and erase. The high density flash EEPROM is integrated into a high performance logic process with dual gate oxides for high performance and high voltage transistors. The array program time is greatly reduced by employing a highly parallel program operation, and data throughput is greatly enhanced by a page mode operation. Operating at 40 MHz, the embedded flash memory has an on-chip off-page access time of under 38 ns and on-page access time of under 13 ns