M29W256GH70N3E Datasheet, PDF (28/76 Pages) Micron Technology – Parallel NOR Flash Embedded Memory

256Mb: 3V Embedded Parallel NOR Flash
Program Operations
Program Operations
PROGRAM Command
The PROGRAM (A0h) command can be used to program a value to one address in the
memory array. The command requires four bus WRITE operations; the final WRITE op-
eration latches the address and data in the internal state machine and starts the pro-
gram/erase controller. After programming has started, bus READ operations output the
status register content.
Programming can be suspended and then resumed by issuing a PROGRAM SUSPEND
command and a PROGRAM RESUME command, respectively.
If the address falls in a protected block, the PROGRAM command is ignored, and the
data remains unchanged. The status register is not read, and no error condition is given.
After the PROGRAM operation has completed, the device returns to read mode, unless
an error has occurred. When an error occurs, bus READ operations to the device contin-
ue to output the status register. A READ/RESET command must be issued to reset the
error condition and return the device to read mode.
The PROGRAM command cannot change a bit set to 0 back to 1, and an attempt to do
so is masked during a PROGRAM operation. Instead, an ERASE command must be used
to set all bits in one memory block or in the entire memory from 0 to 1.
The PROGRAM operation is aborted by performing a reset or by powering-down the de-
vice. In this case, data integrity cannot be ensured, and the words or bytes that were
aborted should be reprogrammed.
UNLOCK BYPASS PROGRAM Command
When the device is in unlock bypass mode, the UNLOCK BYPASS PROGRAM (A0h)
command can be used to program one address in the memory array. The command re-
quires two bus WRITE operations instead of four required by a standard PROGRAM
command; the final WRITE operation latches the address and data and starts the pro-
gram/erase controller. (The standard PROGRAM command requires four bus WRITE
operations.) The PROGRAM operation using the UNLOCK BYPASS PROGRAM com-
mand behaves identically to the PROGRAM operation using the PROGRAM command.
The operation cannot be aborted. A bus READ operation to the memory outputs the
status register.
WRITE TO BUFFER PROGRAM Command
The WRITE TO BUFFER PROGRAM (25h) command makes use of the 32-word program
buffer to speed up programming. A maximum of 32 words can be loaded into the pro-
gram buffer. The WRITE TO BUFFER PROGRAM command dramatically reduces system
programming time compared to the standard non-buffered PROGRAM command.
When issuing a WRITE TO BUFFER PROGRAM command, V _PP/WP# can be either held
HIGH or raised to V_PPH. Also, it can be held LOW if the block is not the lowest or highest
block, depending on the part number. The following successive steps are required to is-
sue the WRITE TO BUFFER PROGRAM command:
First, two UNLOCK cycles are issued. Next, a third bus WRITE cycle sets up the WRITE
TO BUFFER PROGRAM command. The set-up code can be addressed to any location
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