
October 10, 2006  21521D6
Am29LV200B
9
D AT A  S H E E T
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 composed of latches that store the 
commands, along with the address and data informa-
tion needed to execute the command. The contents of 
the register serve as inputs to the internal state 
machine. The state machine outputs dictate the func-
tion of the device. Table 1 lists the device bus 
operations, the inputs and control levels they require, 
and the resulting output. The following subsections 
describe each of these operations in further detail.
Table 1. Am29LV200B 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
 = Addresses In, D
IN
 = Data In, D
OUT
 = Data Out
Notes:
1. Addresses are A16:A0 in word mode (BYTE# = V
IH
), A16: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 con-
trolled 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 
active 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 remain at V
IH
. The BYTE# pin determines 
whether the device 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 memory 
content occurs during the power transition. No 
command 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.
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 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 
includes programming data to the device and erasing 
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