Variable slew rate output driver for high speed, low voltage non-volatile memory

摘要

A low voltage EPROM which increases its reading speed by charging a word line to a voltage higher than Vcc during a read operation. Two voltage pumps, which alternatively place charge on a word line, receive control signals of opposite phase from a temperature insensitive oscillator. The voltage from the two voltage pumps passes through a zero threshold voltage ntype pass device to a word line. The zero threshold voltage n-type pass device receives its control signal from a third voltage pump. In order to make the low voltage EPROM compatible with standard 5V programmers, each output driving circuit consists of a large output driver (55) used under low voltage Vcc conditions and a smaller output driver (57) used under standard 5V Vcc conditions. <IMAGE>