P R E L I M I N A R Y
8
Am29LV160B
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 location.
The register is composed of latches that 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.
Am29LV160B Device Bus Operations
Legend:
L = Logic Low = V
IL
, H = Logic High = V
IH
, V
ID
= 12.0
±
0.5 V, X = Don’t Care, A
IN
= Address In, D
IN
= Data In, D
OUT
= Data Out
Notes:
1. Addresses are A19:A0 in word mode (BYTE# = V
IH
), A19:A-1 in byte mode (BYTE# = V
IL
).
2. The sector protect and sector unprotect functions may also be implemented via programming equipment. See the “Sector
Protection/Unprotection” section.
Word/Byte Configuration
The BYTE# pin controls whether the device data I/O
pins DQ15–DQ0 operate in the byte or word configura-
tion. If the BYTE# pin is set at logic ‘1’, the device is in
word configuration, DQ15–DQ0 are active and control-
led by CE# and OE#.
If the BYTE# pin is set at logic ‘0’, the device is in byte
configuration, and only data I/O pins DQ0–DQ7 are ac-
tive and controlled by CE# and OE#. The data I/O pins
DQ8–DQ14 are tri-stated, and the DQ15 pin is used as
an input for the LSB (A-1) address function.
Requirements for Reading Array Data
To read array data from the outputs, the system must
drive the CE# and OE# pins to V
IL
. CE# is the power
control and selects the device. OE# is the output control
and gates array data to the output pins. WE# should re-
main at V
IH
. The BYTE# pin determines whether the de-
vice outputs array data in words or bytes.
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 mem-
ory content occurs during the power transition. No
command is necessary in this mode to obtain array
data. Standard microprocessor read cycles that as-
sert valid addresses on the device address inputs pro-
duce valid data on the device data outputs. The
device remains enabled for read access until the com-
mand register contents are altered.
See “Reading Array Data” for more information. Refer
to the AC Read Operations table for timing specifica-
tions and to Figure 13 for the timing diagram. I
CC1
in
rent specification for reading array data.
Operation
CE#
L
L
V
CC
±
0.3 V
L
X
OE# WE# RESET#
L
H
H
L
Addresses
(Note 1)
A
IN
A
IN
DQ0–
DQ7
D
OUT
D
IN
DQ8–DQ15
BYTE#
= V
IH
D
OUT
D
IN
BYTE#
= V
IL
Read
Write
H
H
DQ8–DQ14 = High-Z,
DQ15 = A-1
Standby
X
X
V
CC
±
0.3 V
H
L
X
High-Z
High-Z
High-Z
Output Disable
Reset
H
X
H
X
X
X
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
Sector Protect (Note 2)
L
H
L
V
ID
Sector Address,
A6 = L, A1 = H,
A0 = L
Sector Address,
A6 = H, A1 = H,
A0 = L
D
IN
X
X
Sector Unprotect (Note 2)
L
H
L
V
ID
D
IN
X
X
Temporary Sector
Unprotect
X
X
X
V
ID
A
IN
D
IN
D
IN
High-Z