addresses on the device address inputs produce valid
data on the device data outputs. Each bank remains
enabled for read access until the command register
contents are altered.
as required by the Unlock Bypass mode. Removing
VHH from the WP#/ACC pin returns the device to nor-
mal operation. Note that VHH must not be asserted on
WP#/ACC 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.
See “Write Protect (WP#)” on page 15 for related infor-
mation.
Refer to the AC Read-Only Operations table for timing
specifications and to Figure 14 for the timing diagram.
ICC1 in the DC Characteristics table represents the ac-
tive current specification for reading array data.
Writing Commands/Command Sequences
Autoselect Functions
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.
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 DQ15–DQ0. Standard read cycle timings apply in
this mode. Refer to the Autoselect Mode and Autose-
lect Command Sequence sections for more informa-
tion.
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.
The device features an Unlock Bypass mode to facili-
tate faster programming. Once a bank enters the Un-
lock Bypass mode, only two write cycles are required
to program a word or byte, instead of four. The
“Byte/Word Program Command Sequence” section
has details on programming data to the device using
both standard and Unlock Bypass command se-
quences.
Simultaneous Read/Write Operations with
Zero Latency
This device is capable of reading data from one bank
of memory while programming or erasing in the other
bank of memory. An erase operation may also be sus-
pended to read from or program to another location
within the same bank (except the sector being
erased). Figure 21 shows how read and write cycles
may be initiated for simultaneous operation with zero
latency. ICC6 and ICC7 in the DC Characteristics table
represent the current specifications for read-while-pro-
gram and read-while-erase, respectively.
An erase operation can erase one sector, multiple sec-
tors, or the entire device. Table 2 indicates the address
space that each sector occupies. Similarly, a “sector
address” is the address bits required to uniquely select
a sector. The “Command Definitions” section has de-
tails on erasing a sector or the entire chip, or suspend-
ing/resuming the erase operation.
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 address space is divided into four banks. A
“bank address” is the address bits required to uniquely
select a bank.
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.
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.
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 device is deselected during erasure or program-
ming, the device draws active current until the
operation is completed.
If the system asserts VHH 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
ICC3 in the DC Characteristics table represents the
standby current specification.
June 7, 2005
Am29DL640H
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