Preliminary W27E020

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FUNCTIONAL DESCRIPTION

Read Mode

Like conventional UVEPROMs, the W27E020 has two control functions, both of which produce data

at the outputs.

CE is for power control and chip select. OE controls the output buffer to gate data to the output pins.

are met.

Erase Mode

The erase operation is the only way to change data from "0" to "1." Unlike conventional UVEPROMs,

which use ultraviolet light to erase the contents of the entire chip (a procedure that requires up to half

an hour), the W27E020 uses electrical erasure. Generally, the chip can be erased within 100 mS by

using an EPROM writer with a special erase algorithm.

operation.

Erase Verify Mode

After an erase operation, all of the bytes in the chip must be verified to check whether they have been

successfully erased to "1" or not. The erase verify mode automatically ensures a substantial erase

Program Mode

Programming is performed exactly as it is in conventional UVEPROMs, and programming is the only

input pins equal the desired inputs. Pulsing PGM low starts the programming operation.

Program Verify Mode

All of the bytes in the chip must be verified to check whether they have been successfully

programmed with the desired data or not. Hence, after each byte is programmed, a program verify

operation should be performed. The program verify mode automatically ensures a substantial

Erase/Program Inhibit

Erase or program inhibit mode allows parallel erasing or programming of multiple chips with different

CE, the W27E020 may have common inputs.