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7

EN29F080

Rev. C, Issue Date: 2001/07/05

Write Mode

Programming is a four-bus-cycle operation. The program command sequence is initiated by writing two

unlock write cycles, followed by the program set-up command. The program address and data are written

next, which in turn initiate the Embedded Program algorithm. The system is

not required to provide further

controls or timings. The device automatically provides internally generated program pulses and verifies

the programmed cell margin. The Command Definitions in Table 5 show the address and data

requirements for the byte program command sequence.

When the Embedded Program algorithm is complete, the device then returns to reading array data and

addresses are no longer latched. The system can determine the status of the program operation by using

DQ7 or DQ6. See “Write Operation Status” for information on these status bits.

Any commands written to the device during the Embedded Program Algorithm are ignored.

Programming is allowed in any sequence and across sector boundaries. A bit cannot be programmed

from a “0” back to a “1”. Attempting to do so may halt the operation and set DQ5 to “1”, or cause the

Data# Polling algorithm to indicate the operation was successful. However, a succeeding read will show

that the data is still “0”. Only erase operations can convert a “0” to a “1”.

Sector Group Protection/Unprotection

The hardware sector protection feature disables

both program and erase operations in any sector.

Each group consists of two adjacent sectors. The

Sector Group Addresses table shows how the

sectors are grouped, and the address range that

each sector group contains.

The hardware sector

group unprotection feature re-enables both program

and erase operations in previously protected sector

groups.

Sector protection/unprotection must be implemented using programming equipment. The procedure re-

a supplement, which can be obtained by contacting a representative of Eon Silicon Devices, Inc.

Temporary Sector Group Unprotect

This feature allows temporary unprotection of previously protected

sector groups to change data while in-system. The Sector Group

to 11.5 V). During this mode, formerly protected sector groups can be

programmed or erased by simply selecting the sector group

previously protected sector groups are protected again. See

accompanying figure and timing diagrams for more details.

Sector Group Addresses

Sector

Group

A19

A18

A17

Sectors

SGA0

0

0

0

SA0-SA1

SGA1

0

0

1

SA2-SA3

SGA2

0

1

0

SA4-SA5

SGA3

0

1

1

SA6-SA7

SGA4

1

0

0

SA8-SA9

SGA5

1

0

1

SA10-SA11

SGA6

1

1

0

SA12-SA13

SGA7

1

1

1

SA14-SA15

Start

Perform Erase or Program

Operations

Temporary Sector Group

Notes:

1. All protected sector groups unprotected.

2. Previously protected sector groups

protected again.