AM29DL400BB-120SF AMD [Advanced Micro Devices], AM29DL400BB-120SF Datasheet - Page 14

• Manufacturer Part Number: AM29DL400BB-120SF
• 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
Address, SA = Sector Address, X = Don’t care.
Sector Protection/Unprotection
The hardware sector protection feature disables both
program and erase operations in any sector. The
hardware sector unprotection feature re-enables
both program and erase operations in previously
protected sectors. Sector protection/unprotection
can be implemented 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 un-
protect write cycle.
The alternate method intended only for program-
ming equipment requires V
OE#. This method is compatible with programmer
routines written for earlier 3.0 volt-only AMD flash
devices. Publication 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 protect-
ing 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 pro-
tected 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 RESET# pin to V
12
Manufacturer ID: AMD
Device ID:
Am29DL400B
(Top Boot Block)
Device ID:
Am29DL400B
(Bottom Boot Block)
Sector Protection Verification
Description
Table 4. Am29DL400B Autoselect Codes (High Voltage Method)
Mode
ID
Word
Word
Byte
Byte
IL
, H = Logic High = V
(11.5 V – 12.5 V). During this
ID
CE#
L
L
L
L
L
L
on address pin A9 and
ID
on the RESET# pin
OE#
L
L
L
L
L
L
IH
WE#
, BA = Bank
H
H
H
H
H
H
A17
A12
BA
BA
BA
SA
to
Am29DL400B
A11
A10
to
X
X
X
X
V
V
V
V
A9
mode, formerly protected sectors can be pro-
g r a m m e d o r e r a s e d b y s e l e c t i n g t h e s e c t o r
addresses. Once V
pi n , a l l the p re v i ou sl y p r ot e cte d se c tor s a re
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 again.
ID
ID
ID
ID
Figure 1. Temporary Sector Unprotect
A8
A7
to
X
X
X
X
A6
L
L
L
L
A5
A2
to
X
X
X
X
ID
Unprotect Completed
Program Operations
Operation
Temporary Sector
Perform Erase or
A1
is removed from the RESET#
H
L
L
L
RESET# = V
RESET# = V
(Note 1)
(Note 2)
START
A0
H
H
L
L
DQ15
DQ8
ID
22h
22h
IH
to
X
X
X
X
X
(unprotected
(protected)
DQ7
DQ0
01h
01h
00h
0C
0C
to
0F
0F
)