DEVICE BUS OPERATIONS
This section describes the requirements and use of
the device bus operations, which are initiated through
the internal command register. The command register
itself does not occupy any addressable memory loca-
tion. The register is a latch used to store the com-
mands, along with the address and data information
needed to execute the command. The contents of the
register serve as inputs to the internal state machine.
The state machine outputs dictate the function of the
device. Table 1 lists the device bus operations, the in-
puts and control levels they require, and the resulting
output. The following subsections describe each of
these operations in further detail.
Table 1. Am29DL640H Device Bus Operations
DQ15–DQ8
BYTE#
Addresses
(Note 2)
BYTE#
= VIH
DQ7–
DQ0
Operation
CE# OE# WE# RESET# WP#/ACC
= VIL
Read
Write
L
L
L
H
L
H
H
L/H
AIN
AIN
DOUT
DIN
DOUT
DIN
DQ14–DQ8 =
High-Z, DQ15 = A-1
H
(Note 3)
VCC
0.3 V
±
VCC ±
0.3 V
Standby
X
X
L/H
X
High-Z
High-Z
High-Z
Output Disable
Reset
L
H
X
H
X
H
L
L/H
L/H
X
X
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
X
SA, A6 = L,
A1 = H, A0 = L
Sector Protect (Note 2)
L
L
X
H
H
X
L
L
X
VID
VID
VID
L/H
X
X
X
X
DIN
DIN
DIN
SA, A6 = H,
A1 = H, A0 = L
Sector Unprotect (Note 2)
(Note 3)
(Note 3)
Temporary Sector
Unprotect
AIN
DIN
High-Z
Legend: L = Logic Low = VIL, H = Logic High = VIH, VID = 11.5–12.5 V, VHH = 9.0 ± 0.5 V, X = Don’t Care, SA = Sector Address,
AIN = Address In, DIN = Data In, DOUT = Data Out
Notes:
1. Addresses are A21:A0 in word mode (BYTE# = VIH), A21:A-1 in byte mode (BYTE# = VIL).
2. The sector protect and sector unprotect functions may also be implemented via programming equipment. See the “Sector/Sector
Block Protection and Unprotection” section.
3. If WP#/ACC = VIL, sectors 0, 1, 140, and 141 remain protected. If WP#/ACC = VIH, protection on sectors 0, 1, 140, and 141
depends on whether they were last protected or unprotected using the method described in “Sector/Sector Block Protection
and Unprotection”. If WP#/ACC = VHH, all sectors will be unprotected.
Word/Byte Configuration
Requirements for Reading Array Data
The BYTE# pin controls whether the device data I/O
pins operate in the byte or word configuration. If the
BYTE# pin is set at logic ‘1’, the device is in word con-
figuration, DQ15–DQ0 are active and controlled by
CE# and OE#.
To read array data from the outputs, the system must
drive the CE# and OE# pins to VIL. CE# 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 BYTE# pin determines
whether the device outputs array data in words or
bytes.
If the BYTE# 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# 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.
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
8
Am29DL640H
June 7, 2005
SPANSION [ SPANSION ]
