M28R400CTB120ZB1T Ver la hoja de datos (PDF) - STMicroelectronics

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M28R400CTB120ZB1T

4 Mbit (256Kb x16, Boot Block) 1.8V Supply Flash Memory

STMicroelectronics 

M28R400CT, M28R400CB

During the erase operation the memory will only

accept the Read Status Register command. All

other commands will be ignored, including the

Erase Suspend command. It is not possible to is-

sue any command to abort the operation.

Chip Erase commands should be limited to a max-

imum of 100 Program/Erase cycles. After 100 Pro-

gram/Erase cycles the internal algorithm will still

operate properly but some degradation in perfor-

mance may occur.

Typical chip erase times are given in Table 7.

Program Command

The memory array can be programmed word-by-

word. Two bus write cycles are required to issue

the Program Command.

s The first bus cycle sets up the Program

command.

s The second latches the Address and the Data to

be written and starts the Program/Erase

Controller.

During Program operations the memory will ac-

cept the Read Status Register command and the

Program/Erase Suspend command. Typical Pro-

gram times are given in Table 7, Program, Erase

Times and Program/Erase Endurance Cycles.

Programming aborts if Reset goes to VIL. As data

integrity cannot be guaranteed when the program

operation is aborted, the block containing the

memory location must be erased and repro-

grammed.

See Appendix C, Figure 15, Program Flowchart

and Pseudo Code, for the flowchart for using the

Program command.

Double Word Program Command

This feature is offered to improve the programming

throughput, writing a page of two adjacent words

in parallel.The two words must differ only for the

address A0. Programming should not be attempt-

ed when VPP is not at VPPH. The command can be

executed if VPP is below VPPH but the result is not

guaranteed.

Three bus write cycles are necessary to issue the

Double Word Program command.

s The first bus cycle sets up the Double Word

Program Command.

s The second bus cycle latches the Address and

the Data of the first word to be written.

s The third bus cycle latches the Address and the

Data of the second word to be written and starts

the Program/Erase Controller.

Read operations output the Status Register con-

tent after the programming has started. Program-

ming aborts if Reset goes to VIL. As data integrity

cannot be guaranteed when the program opera-

tion is aborted, the block containing the memory

location must be erased and reprogrammed.

See Appendix C, Figure 16, Double Word Pro-

gram Flowchart and Pseudo Code, for the flow-

chart for using the Double Word Program

command.

Clear Status Register Command

The Clear Status Register command can be used

to reset bits 1, 3, 4 and 5 in the Status Register to

‘0’. One bus write cycle is required to issue the

Clear Status Register command.

The bits in the Status Register do not automatical-

ly return to ‘0’ when a new Program or Erase com-

mand is issued. The error bits in the Status

Register should be cleared before attempting a

new Program or Erase command.

Program/Erase Suspend Command

The Program/Erase Suspend command is used to

pause a Program or Erase operation. One bus

write cycle is required to issue the Program/Erase

command and pause the Program/Erase control-

ler.

During Program/Erase Suspend the Command In-

terface will accept the Program/Erase Resume,

Read Array, Read Status Register, Read Electron-

ic Signature and Read CFI Query commands. Ad-

ditionally, if the suspend operation was Erase then

the Program, Block Lock, Block Lock-Down or

Protection Program commands will also be ac-

cepted. The block being erased may be protected

by issuing the Block Protect, Block Lock or Protec-

tion Program commands. When the Program/

Erase Resume command is issued the operation

will complete. Only the blocks not being erased

may be read or programmed correctly.

During a Program/Erase Suspend, the device can

be placed in a pseudo-standby mode by taking

Chip Enable to VIH. Program/Erase is aborted if

Reset turns to VIL.

See Appendix C, Figure 17, Program Suspend &

Resume Flowchart and Pseudo Code, and Figure

19, Erase Suspend & Resume Flowchart and

Pseudo Code for flowcharts for using the Program/

Erase Suspend command.

Program/Erase Resume Command

The Program/Erase Resume command can be

used to restart the Program/Erase Controller after

a Program/Erase Suspend operation has paused

it. One Bus Write cycle is required to issue the

command. Once the command is issued subse-

quent Bus Read operations read the Status Reg-

ister.

See Appendix C, Figure 17, Program Suspend &

Resume Flowchart and Pseudo Code, and Figure

19, Erase Suspend & Resume Flowchart and

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