M29W400 データシートの表示（PDF） - STMicroelectronics

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M29W400

4 Mbit (512Kb x8 or 256Kb x16, Boot Block) Low Voltage Single Supply Flash Memory

STMicroelectronics 

Figure 7. Write AC Waveforms, W Controlled

M29W400T, M29W400B

A0-A17/

A–1

E

G

W

DQ0-DQ7/

DQ8-DQ15

VCC

RB

tAVWL

tELWL

tGHWL

tVCHEL

tAVAV

VALID

tWLAX

tWHEH

tWHGL

tWLWH

tDVWH

VALID

tWHWL

tWHDX

tWHRL

AI01869C

Note: Address are latched on the falling edge of W, Data is latched on the rising edge of W.

During the executionof theerase by the P/E.C.,the

memory accepts only the Erase Suspend ES and

Read/Reset RD instructions. Data Polling bit DQ7

returns ’0’ while the erasure is in progress and ’1’

when it has completed. The Toggle bit DQ2 and

DQ6 toggle during the erase operation. They stop

when erase is completed. After completion the

Status Register bit DQ5 returns’1’ if there has been

an erase failure. In such a situation, the Toggle bit

DQ2 can be used to determine which block is not

correctly erased. In the case of erase failure, a

Read/Reset RD instruction is necessary in order to

reset the P/E.C.

Chip Erase(CE) Instruction. This instructionuses

six write cycles. The Erase Set-up command 80h

is written to address AAAAh in the Byte-wide con-

figuration or the address 5555h in the Word-wide

configurationon the third cycle after the two Coded

cycles. The Chip Erase Confirm command 10h is

similarly written on the sixth cycle after another two

Coded cycles. If the second command given is not

an erase confirm or if the Coded cycles are wrong,

the instruction aborts and the device is reset to

Read Array. It is not necessaryto programthe array

with 00h first as the P/E.C. will automaticallydo this

before erasing it to FFh. Read operations after the

sixth rising edge of W or E output the Status

Register bits. During the execution of the erase by

the P/E.C., Data Polling bit DQ7 returns ’0’, then ’1’

on completion. The Toggle bits DQ2 and DQ6

toggle during erase operation and stop when erase

is completed. After completion the Status Register

bit DQ5 returns ’1’ if there has been an Erase

Failure.

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