M29W640FT datasheet(11/72 Pages) STMICROELECTRONICS

11 / 72 page

M29W640FT, M29W640FB

2 Signal descriptions

11/72

Signal descriptions

See Figure 1: Logic Diagram, and Table 1: Signal Names, for a brief overview of the signals

connected to this device.

2.1

Address Inputs (A0-A21)

The Address Inputs select the cells in the memory array to access during Bus Read operations.

During Bus Write operations they control the commands sent to the Command Interface of the

Program/Erase Controller.

2.2

Data Inputs/Outputs (DQ0-DQ7)

The Data I/O outputs the data stored at the selected address during a Bus Read operation.

During Bus Write operations they represent the commands sent to the Command Interface of

the Program/Erase Controller.

2.3

Data Inputs/Outputs (DQ8-DQ14)

The Data I/O outputs the data stored at the selected address during a Bus Read operation

when BYTE is High, VIH. When BYTE is Low, VIL, these pins are not used and are high

impedance. During Bus Write operations the Command Register does not use these bits.

When reading the Status Register these bits should be ignored.

2.4

Data Input/Output or Address Input (DQ15A

–1)

When BYTE is High, VIH, this pin behaves as a Data Input/Output pin (as DQ8-DQ14). When

BYTE is Low, VIL, this pin behaves as an address pin; DQ15A–1 Low will select the LSB of the

addressed Word, DQ15A

–1 High will select the MSB. Throughout the text consider references

to the Data Input/Output to include this pin when BYTE is High and references to the Address

Inputs to include this pin when BYTE is Low except when stated explicitly otherwise.

2.5

Chip Enable (E)

The Chip Enable, E, activates the memory, allowing Bus Read and Bus Write operations to be

performed. When Chip Enable is High, VIH, all other pins are ignored.

2.6

Output Enable (G)

The Output Enable, G, controls the Bus Read operation of the memory.

M29W640FT Datasheet(PDF) 11 Page - STMicroelectronics