AM29LV004B-1 AMD [Advanced Micro Devices], AM29LV004B-1 Datasheet - Page 12

• Manufacturer Part Number: AM29LV004B-1
• Description: 4 Megabit (512 K x 8-Bit) CMOS 3.0 Volt-only Boot Sector Flash Memory
• Manufacturer: AMD [Advanced Micro Devices]

Autoselect Mode
The autoselect mode provides manufacturer and
device identification, and sector protection verification,
through identifier codes output on DQ7–DQ0. This
mode is primarily intended for programming equipment
to automatically match a device to be programmed with
its corresponding programming algorithm. However,
the autoselect codes can also be accessed in-system
through the command register.
When using programming equipment, the autoselect
mode requires V
A9. Address pins A6, A1, and A0 must be as shown in
L = Logic Low = V
Sector Protection/Unprotection
The hardware sector protection feature disables both
program and erase operations in any sector. The hard-
ware sector unprotection feature re-enables both
program and erase operations in previously protected
sectors. Sector protection/unprotection can be imple-
mented via two methods.
The primary method requires V
only, and can be implemented either in-system or via
programming equipment. Figure 1 shows the algo-
rithms and Figure 21 shows the timing diagram. This
method uses standard microprocessor bus cycle
timing. For sector unprotect, all unprotected sectors
must first be protected prior to the first sector unprotect
write cycle.
The alternate method intended only for programming
equipment requires V
RESET#. This method is compatible with programmer
routines written for earlier 3.0 volt-only AMD flash
devices. Publication number 20874 contains further
Manufacturer ID: AMD
Device ID: Am29LV004BT
(Top Boot Block)
Device ID: Am29LV004BB
(Bottom Boot Block)
Sector Protection Verification
Description
IL
ID
, H = Logic High = V
(11.5 V to 12.5 V) on address pin
ID
Table 4. Am29LV004B Autoselect Codes (High Voltage Method)
on address pin A9, OE#, and
ID
on the RESET# pin
CE#
IH
L
L
L
L
, SA = Sector Address, X = Don’t care.
OE#
L
L
L
L
WE#
H
H
H
H
Am29LV004B
A18
A13
SA
to
X
X
X
Table 4. In addition, when verifying sector protection,
the sector address must appear on the appropriate
highest order address bits (see Tables 2 and 3). Table
4 shows the remaining address bits that are don’t care.
When all necessary bits have been set as required, the
programming equipment may then read the corre-
sponding identifier code on DQ7–DQ0.
To access the autoselect codes in-system, the host
system can issue the autoselect command via the
command register, as shown in Table 5. This method
does not require V
details on using the autoselect mode.
details; contact an AMD representative to request a
copy.
The device is shipped with all sectors unprotected.
AMD offers the option of programming and protecting
sectors at its factory prior to shipping the device
through AMD’s ExpressFlash™ Service. Contact an
AMD representative for details.
It is possible to determine whether a sector is protected
or unprotected. See “Autoselect Mode” for details.
Temporary Sector Unprotect
This feature allows temporary unprotection of previ-
ously protected sectors to change data in-system. The
Sector Unprotect mode is activated by setting the
RESET# pin to V
tected sectors can be programmed or erased by
selecting the sector addresses. Once V
from the RESET# pin, all the previously protected
sectors are protected again. Figure 2 shows the algo-
rithm, and Figure 20 shows the timing diagrams, for this
feature.
A12
A10
to
X
X
X
X
V
V
V
V
A9
ID
ID
ID
ID
A8
A7
to
X
X
X
X
ID
A6
ID
L
L
L
L
. During this mode, formerly pro-
. See “Command Definitions” for
A5
A2
to
X
X
X
X
A1
H
L
L
L
A0
H
H
L
L
ID
(unprotected)
(protected)
is removed
DQ7
DQ0
01h
B5h
B6h
01h
00h
to
11