28F160S5, 28F320S5 E
26 ADVANCE INFORMATION
This two-s tep command s equence of set up f ol l owed
by execution ensures that block contents are not
accidentally erased. An invalid Full Chip Erase
command sequence will result in both Status
Register bits SR.4 and SR.5 being set to 1. Also,
reliable full chip erasure can only occur when
VCC = VCC1/2 and V PP = VPPH. In t he absence these
voltages, block contents are protected against
erasure.
If full chip erase is attempted while VPP ≤
VPPLK, SR.3 and S R.5 will be s et to 1. When WP# =
VIL, only unlocked blocks are erased. Full chip
erase cannot be suspended.
4.8 Write to Buffer Command
To program the flash device via the writ e buffers, a
Write to Buffer command sequence is initiated. A
variable number of bytes or words, up to the buffer
size, can be wri tt en into the buf fer and program med
to the flash device. First, the Write to Buffer setup
command is issued along with the Block Address.
At this point, the eXtended Status Register
information is loaded and XSR.7 reverts to the
“buffer available” status. If XSR.7 = 0, no write
buffer is available. To retry, continue monitoring
XSR.7 by issuing the Write to Buffer setup
command with the Block Address until XSR.7 = 1.
When XSR.7 transit ions to a “1,” the buf fer is ready
for loading.
Now a Word/Byte count is issued at an address
within the block. On the next write, a device start
address is given along with the write buffer data.
For maximum programm ing performance and lower
power, align the start address at the beginni ng of a
Write Buffer boundary. Subsequent writes must
supply additional device addresses and data,
depending on the count. All subsequent addresses
must lie within the start address plus the count.
After the final buffer data is given, a Write Confirm
command is issued. This initiates the WS M to begi n
copying the buffer data to the flash memory. If a
command other than Write Conf irm is written t o the
device, an “Invalid Command/Sequence” error will
be generated and Status Register bits SR.5 and
SR.4 will be set to “1.” For additional buffer writes,
issue another Write to Buffer setup command and
check XSR.7. The write buf fers can be l oaded while
the WSM is bus y as long as X SR.7 indicat es that a
buffer is available. Refer to Fi gure 6 for the Write t o
Buffer flowchart.
If an error occurs while writing, the device will stop
programming, and Status Register bit SR.4 will be
set to a “1” to indicate a program fail ure. Any t ime a
media failure occurs during a program or an erase
(SR.4 or SR.5 is set), the device will not accept any
more Write to Buffer commands. Additionally, if the
user attempts to wri te past an erase bloc k boundary
with a Write to Buffer command, the device will
abort programming. This will generate an “Invalid
Command/S equence” error and Status Register bits
SR.5 and SR.4 will be set to “1.” To clear SR.4
and/or SR.5, issue a Clear Status Register
command.
Reliable buffered programming can only occur
when VCC = VCC1/2 and VPP = VPPH. If programm ing
is attempted while VPP ≤ VPPLK, Status Regis ter bit s
SR.4 and SR.5 will be set to “1.” Programming
attempts with invalid VCC and VPP voltages produc e
spurious results and should not be attempted.
Finally, successful programming requires that the
corresponding B lock Lock -Bit be cleared, or WP# =
VIH. If a buffered write is attempted when the
corresponding B lock Loc k-Bit is s et and WP# = VIL,
SR.1 and SR.4 will be set to “1.”
4.9 Byte/Word Program Command
Byte/Word programming is executed by a two-cycle
command sequence. Byte/Word Program setup
(standard 40H or alternate 10H) is written, followed
by a second write that specifies the address and
data (latched on t he risi ng edge of WE #). The WSM
then takes over, controlling the program and verify
algorithms internally. After the write sequence is
written, the device automatically outputs Status
Register data when read. The CPU can detect the
completion of the program event by analyzing STS
in level RY/BY# mode or Status Register bit SR.7.
When programming is c omplete, Status Register bi t
SR.4 should be checked. If a programming error is
detected, the Status Register should be cleared.
The internal WSM verify onl y detects errors for “1”s
that do not successfully program to “0”s. The CUI
remains in read Status Register mode until it
receives another command. Refer to Figure 7 for
the Word/Byte Program flowchart.
Also, Reliable byte/word programming can only
occur when VCC = VCC1/2 and VPP = VPPH. In the
absence of thi s high v olt age, c ontent s are prot ect ed
against programming. If a byte/word program is