AM29DL400BB-120EC AMD [Advanced Micro Devices], AM29DL400BB-120EC Datasheet - Page 13

• Manufacturer Part Number: AM29DL400BB-120EC
• Description: 4 Megabit (512 K x 8-Bit/256 K x 16-Bit) CMOS 3.0 Volt-only, Simultaneous Operation Flash Memory
• Manufacturer: AMD [Advanced Micro Devices]

Note: 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 pro-
gram 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 2 shows the algo-
rithms and Figure 24 shows the timing diagram. This
method uses standard microprocessor bus cycle tim-
ing. 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
This method is compatible with programmer routines
written for earlier 3.0 volt-only AMD flash devices. Pub-
lication number 22145 contains further 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 the Autoselect Mode section 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 RE-
Manufacturer ID: AMD
Device ID:
Am29DL400B
(Top Boot Block)
Device ID:
Am29DL400B
(Bottom Boot Block)
Sector Protection Verification
Description
Mode
Word
Word
Byte
Byte
IL
ID
Table 4. Am29DL400B Autoselect Codes (High Voltage Method)
, H = Logic High = V
on address pin A9 and OE#.
CE#
L
L
L
L
L
L
ID
on the RESET# pin
OE#
L
L
L
L
L
L
WE#
IH
H
H
H
H
H
H
P R E L I M I N A R Y
, BA = Bank Address, SA = Sector Address, X = Don’t care.
A17
A12
BA
BA
BA
SA
to
Am29DL400B
A11
A10
to
X
X
X
X
V
V
V
V
A9
SET# pin to V
formerly protected sectors can be programmed or
erased by selecting the sector addresses. Once V
removed from the RESET# pin, all the previously pro-
tected sectors are protected again. Figure 1 shows the
algorithm, and Figure 23 shows the timing diagrams,
for this feature.
Notes:
1. All protected sectors unprotected.
2. All previously protected sectors are protected once
Figure 1. Temporary Sector Unprotect Operation
ID
ID
ID
ID
again.
A8
A7
to
X
X
X
X
A6
L
L
L
L
ID
A5
A2
(11.5 V – 12.5 V). During this mode,
to
X
X
X
X
Unprotect Completed
Program Operations
Temporary Sector
Perform Erase or
A1
H
L
L
L
RESET# = V
RESET# = V
(Note 1)
(Note 2)
START
A0
H
H
L
L
DQ15
DQ8
22h
22h
ID
IH
to
X
X
X
X
X
(unprotected)
(protected)
DQ7
DQ0
01h
01h
00h
21606C-5
0C
0C
0F
0F
to
ID
13
is