10
Am29LV320D
July 30, 2002
The internal state machine is set for reading array data
upon device power-up, or after a hardware reset. This
ensures that no spurious alteration of the memory
content occurs during the power transition. No com-
mand is necessary in this mode to obtain array data.
Standard microprocessor read cycles that assert valid
addresses on the device address inputs produce valid
data on the device data outputs. The device remains
enabled for read access until the command register
contents are altered.
table for timing specifications and to
Figure 14 for the
timing diagram. I
CC1 in the DC Characteristics table
represents the active current specification for reading
array 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 V
IL, and OE# to VIH.
For program operations, the BYTE# pin determines
whether the device accepts program data in bytes or
formation.
The device features an Unlock Bypass mode to facil-
itate 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
gramming data to the device using both standard and
Unlock Bypass command sequences.
An erase operation can erase one sector, multiple sec-
tors, or the entire device. Tables
2–5 indicate the ad-
dress space that each sector occupies. A “sector
address” is the address bits required to uniquely select
a sector.
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CC2 in the DC Characteristics table represents the ac-
tive current specification for the write mode. The
ACtables and timing diagrams for write operations.
Accelerated Program Operation
The device offers accelerated program operations
through the ACC function. This is one of two functions
provided by the WP#/ACC pin. This function is prima-
rily intended to allow faster manufacturing throughput
at the factory.
If the system asserts V
HH on this pin, the device auto-
matically enters the aforementioned Unlock Bypass
mode, temporarily unprotects any protected sectors,
and uses the higher voltage on the pin to reduce the
time required for program operations. The system
would use a two-cycle program command sequence
as required by the Unlock Bypass mode. Removing
V
HH from the WP#/ACC pin returns the device to nor-
mal operation. Note that the WP#/ACC pin must not
be at V
HH for operations other than accelerated pro-
gramming, or device damage may result. In addition,
the WP#/ACC pin must not be left floating or uncon-
nected; inconsistent behavior of the device may result.
Autoselect Functions
If 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
tion.
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the current specifications for read-while-program and
read-while-erase, respectively.
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,
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 V
CC ± 0.3 V.
(Note that this is a more restricted voltage range than
V
IH.) If CE# and RESET# are held at VIH, but not within
V
CC ± 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 (t
CE) for read access
when the device is in either of these standby modes,
before it is ready to read data.
If the device is deselected during erasure or program-
ming, the device draws act ive current until t he
operation is completed.
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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 t
ACC +
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.
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automatic sleep mode current specification.