D A T A S H E E T
tions and to Figure 13 for the timing diagram. ICC1 in
the DC Characteristics table represents the active cur-
rent specification for reading array data.
and the outputs are placed in the high impedance
state, independent of the OE# input.
The device enters the CMOS standby mode when the
CE# and RESET# pins are both held at VCC ± 0.3 V.
(Note that this is a more restricted voltage range than
VIH.) If CE# and RESET# are held at VIH, but not within
VCC ± 0.3 V, the device will be in the standby mode, but
the standby current will be greater. The device re-
quires standard access time (tCE) for read access
when the device is in either of these standby modes,
before it is ready to read data.
Writing Commands/Command Sequences
To write a command or command sequence (which in-
cludes programming data to the device and erasing
sectors of memory), the system must drive WE# and
CE# to VIL, and OE# to VIH.
For program operations, the BYTE# pin determines
whether the device accepts program data in bytes or
words. Refer to “Word/Byte Configuration” for more in-
formation.
If the device is deselected during erasure or program-
ming, the device draws active current until the
operation is completed.
The device features an Unlock Bypass mode to facili-
tate faster programming. Once the device enters the
Unlock Bypass mode, only two write cycles are re-
quired to program a word or byte, instead of four. The
“Word/Byte Program Command Sequence” section
has details on programming data to the device using
both standard and Unlock Bypass command se-
quences.
ICC3 in the DC Characteristics table represents the
standby current specification.
Automatic Sleep Mode
The automatic sleep mode minimizes Flash device en-
ergy consumption. The device automatically enables
this mode when addresses remain stable for tACC + 30
ns. The automatic sleep mode is independent of the
CE#, WE#, and OE# control signals. Standard ad-
dress access timings provide new data when ad-
dresses are changed. While in sleep mode, output
data is latched and always available to the system.
An erase operation can erase one sector, multiple sec-
tors, or the entire device. Tables 2 and 3 indicate the
address space that each sector occupies. A “sector
address” consists of the address bits required to
uniquely select a sector. The “Command Definitions”
section has details on erasing a sector or the entire
chip, or suspending/resuming the erase operation.
ICC4 in the DC Characteristics table represents the au-
tomatic sleep mode current specification.
After the system writes the autoselect command se-
quence, the device enters the autoselect mode. The
system can then read autoselect codes from the inter-
nal register (which is separate from the memory array)
on DQ7–DQ0. Standard read cycle timings apply in
this mode. Refer to the Autoselect Mode and Autose-
lect Command Sequence sections for more informa-
tion.
RESET#: Hardware Reset Pin
The RESET# pin provides a hardware method of re-
setting the device to reading array data. When the RE-
SET# pin is driven low for at least a period of tRP, the
device immediately terminates any operation in
progress, tristates all output pins, and ignores all
read/write commands for the duration of the RESET#
pulse. The device also resets the internal state ma-
chine to reading array data. The operation that was in-
terrupted should be reinitiated once the device is
ready to accept another command sequence, to en-
sure data integrity.
ICC2 in the DC Characteristics table represents the ac-
tive current specification for the write mode. The “AC
Characteristics” section contains timing specification
tables and timing diagrams for write operations.
Current is reduced for the duration of the RESET#
pulse. When RESET# is held at VSS 0.3 V, the device
draws CMOS standby current (ICC4). If RESET# is held
at VIL but not within VSS 0.3 V, the standby current will
be greater.
Program and Erase Operation Status
During an erase or program operation, the system
may check the status of the operation by reading the
status bits on DQ7–DQ0. Standard read cycle timings
and ICC read specifications apply. Refer to “Write Op-
eration Status” for more information, and to “AC Char-
acteristics” for timing diagrams.
If RESET# is asserted during a program or erase op-
eration, the RY/BY# pin remains a “0” (busy) until the
internal reset operation is complete, which requires a
time of tREADY (during Embedded Algorithms). The sys-
tem can thus monitor RY/BY# to determine whether
the reset operation is complete. If RESET# is asserted
when a program or erase operation is not executing
(RY/BY# pin is “1”), the reset operation is completed
within a time of tREADY (not during Embedded Algo-
Standby Mode
When the system is not reading or writing to the de-
vice, it can place the device in the standby mode. In
this mode, current consumption is greatly reduced,
10
Am29LV400B
21523D4 December 4, 2006
SPANSION [ SPANSION ]
