AM29LV642D AMD [Advanced Micro Devices], AM29LV642D Datasheet - Page 25

• Manufacturer Part Number: AM29LV642D
• Manufacturer: AMD [Advanced Micro Devices]

Hardware Data Protection
The command sequence requirement of unlock cycles
for programming or erasing provides data protection
against inadvertent writes (refer to Table 10 for com-
mand definitions). In addition, the following hardware
data protection measures prevent accidental erasure
or programming, which might otherwise be caused by
spurious system level signals during V
and power-down transitions, or from system noise.
Low V
When V
cept any write cycles. This protects data during V
power-up and power-down. The command register
and all internal program/erase circuits are disabled,
and the device resets to the read mode. Subsequent
writes are ignored until V
system must provide the proper signals to the control
COMMON FLASH MEMORY INTERFACE (CFI)
The Common Flash Interface (CFI) specification out-
lines device and host system software interrogation
handshake, which allows specific vendor-specified
software algorithms to be used for entire families of
devices. Software support can then be device-inde-
pendent, JEDEC ID-independent, and forward- and
backward-compatible for the specified flash device
families. Flash vendors can standardize their existing
interfaces for long-term compatibility.
The Am29LV642 is a two die solution which appears
as two 64 Mbit Am29LV640 devices in the system.
This allows the same CFI information to be used be-
cause the system “sees” two 64 Mbit devices, not a
single 128 Mbit device.
This device enters the CFI Query mode when the sys-
tem writes the CFI Query command, 98h, to address
May 5, 2006 25022A2
Addresses (x16)
CC
1Ah
10h
11h
12h
13h
14h
15h
16h
17h
18h
19h
CC
Write Inhibit
is less than V
LKO
0051h
0052h
0059h
0002h
0000h
0040h
0000h
0000h
0000h
0000h
0000h
CC
Data
, the device does not ac-
is greater than V
Table 6. CFI Query Identification String
Query Unique ASCII string “QRY”
Primary OEM Command Set
Address for Primary Extended Table
Alternate OEM Command Set (00h = none exists)
Address for Alternate OEM Extended Table (00h = none exists)
CC
D A T A
power-up
LKO
. The
Am29LV642D
CC
S H E E T
pins to prevent unintentional writes when V
greater than V
Write Pulse “Glitch” Protection
Noise pulses of less than 5 ns (typical) on OE#, CE#,
CE2#, or WE# do not initiate a write cycle.
Logical Inhibit
Write cycles are inhibited by holding any one of OE# =
V
write cycle, CE# (or CE2#), and WE# must be a logical
zero while OE# is a logical one.
Power-Up Write Inhibit
If WE# = CE# = CE2# = V
power up, the device does not accept commands on
the rising edge of WE#. The internal state machine is
automatically reset to the read mode on power-up.
55h anytime the device is ready to read array data.
The system can read CFI information at the addresses
given in Tables 6–9. To terminate reading CFI data,
the system must write the reset command.
The system can also write the CFI query command
when the device is in the autoselect mode. The device
enters the CFI query mode, and the system can read
CFI data at the addresses given in Tables 6–9. The
system must write the reset command to return the
device to the autoselect mode.
For further information, please refer to the CFI Specifi-
cation and CFI Publication 100, available via the World
Wide Web at http://www.amd.com/products/nvd/over-
view/cfi.html. Alternatively, contact an AMD represen-
tative for copies of these documents.
IL
, CE# = V
Description
IH
LKO
, CE2# = V
.
IH
or WE# = V
IL
and OE# = V
IH
. To initiate a
IH
during
CC
23
is