P R E L I M I N A R Y
An erase operation can erase one sector, multiple sec-
FLASH DEVICE BUS OPERATIONS
Word/Byte Configuration
tors, or the entire device. Table 3 indicates the address
space that each sector occupies. Similarly, a “sector
address” is the address bits required to uniquely select
a sector. The “Flash Command Definitions” section
has details on erasing a sector or the entire chip, or
suspending/resuming the erase operation.
The CIOf pin controls whether the device data I/O pins
operate in the byte or word configuration. If the CIOf
pin is set at logic ‘1’, the device is in word configura-
tion, DQ15–DQ0 are active and controlled by CE#f
and OE#.
The device address space is divided into four banks. A
“bank address” is the address bits required to uniquely
select a bank.
If the CIOf pin is set at logic ‘0’, the device is in byte
configuration, and only data I/O pins DQ7–DQ0 are
active and controlled by CE#f and OE#. The data I/O
pins DQ14–DQ8 are tri-stated, and the DQ15 pin is
used as an input for the LSB (A-1) address function.
ICC2 in the DC Characteristics table represents the ac-
tive current specification for the write mode. The Flash
AC Characteristics section contains timing specifica-
tion tables and timing diagrams for write operations.
Requirements for Reading Array Data
Accelerated Program Operation
To read array data from the outputs, the system must
drive the CE#f and OE# pins to VIL. CE#f is the power
control and selects the device. OE# is the output con-
trol and gates array data to the output pins. WE#
should remain at VIH. The CIOf pin determines
whether the device outputs array data in words or
bytes.
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 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
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 19 for related in-
formation.
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. Each bank remains
enabled for read access until the command register
contents are altered.
Refer to the Flash Read-Only Operations table for tim-
ing specifications and to Figure 14 for the timing dia-
gram. ICC1 in the DC Characteristics table represents
the active current specification for reading array data.
Autoselect Functions
Writing Commands/Command Sequences
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.
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#f to VIL, and OE# to VIH.
For program operations, the CIOf pin determines
whether the device accepts program data in bytes or
words. Refer to “Flash Device Bus Operations” for
more information.
Simultaneous Read/Write Operations with
Zero Latency
The device features an Unlock Bypass mode to facil-
itate 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.
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
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Am49DL32xBG
July 19, 2002
CYPRESS [ CYPRESS ]
