M28R400CT, M28R400CB
pears to start but will terminate, leaving the data
unchanged. No error condition is given when pro-
tected blocks are ignored.
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.
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.
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.
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.
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.
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 first bus cycle sets up the Program
command.
The second latches the Address and the Data
to be written and starts the Program/Erase
Controller.
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 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.
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.
See APPENDIX C., Figure 15., Program Flow-
chart and Pseudo Code, for the flowchart for using
the Program command.
Double Word Program Command
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 Fig-
ure 19., Erase Suspend & Resume Flowchart and
Pseudo Code, for flowcharts for using the Pro-
gram/Erase Suspend 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.
Program/Erase Resume Command
■
■
■
The first bus cycle sets up the Double Word
Program Command.
The second bus cycle latches the Address and
the Data of the first word to be written.
The third bus cycle latches the Address and
the Data of the second word to be written and
starts the Program/Erase Controller.
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 Fig-
Read operations output the Status Register con-
tent after the programming has started. Program-
11/48
NUMONYX [ NUMONYX B.V ]
