A D V A N C E I N F O R M A T I O N
address must appear on the appropriate highest order
Autoselect Mode
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 program-
ming equipment may then read the corresponding
identifier code on DQ7–DQ0.
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.
To access the autoselect codes in-system, the host
system can issue the autoselect command via the
command register, as shown in Table 5 on page 17.
This method does not require VID. See “ Command
Definitions, on page 13 for details on using the autose-
lect mode.
When using programming equipment, the autoselect
mode requires VID on address pin A9. Address pins
A6, A1, and A0 must be as shown in Table 4. In addi-
tion, when verifying sector protection, the sector
Table 4. Am29SL400D Autoselect Codes (High Voltage Method)
A17 A11
to to
Mode CE# OE# WE# A12 A10 A9
A8
to
A7
A5
to
A2
DQ8
to
A0 DQ15
DQ7
to
DQ0
Description
A6
A1
Manufacturer ID: AMD
L
L
L
L
H
H
X
X
V
X
X
L
X
X
L
L
X
01h
70h
ID
Device ID:
Am29SL400D
(Top Boot Block)
Word
Byte
Word
Byte
22h
X
X
V
L
L
L
L
H
ID
L
L
L
L
L
L
H
H
H
X
22h
X
70h
F1h
F1h
Device ID:
Am29SL400D
(Bottom Boot Block)
X
X
X
V
V
X
X
X
X
H
L
ID
01h
(protected)
X
X
Sector Protection Verification
L
L
H
SA
L
H
ID
00h
(unprotected)
L = Logic Low = V , H = Logic High = V , SA = Sector Address, X = Don’t care.
IL
IH
through AMD’s ExpressFlash™ Service. Contact an
AMD representative for details.
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.
It is possible to determine whether a sector is protected
or unprotected. See Autoselect Mode, on page 11 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
Sector protection/unprotection requires V on the
ID
RESET# pin only, and can be implemented either
in-system or via programming equipment. Figure 1, on
page 12 shows the algorithms and Figure 23, on
page 34 shows the timing diagram. This method uses
standard microprocessor bus cycle timing. For sector
unprotect, all unprotected sectors must first be pro-
tected prior to the first sector unprotect write cycle.
RESET# pin to V . During this mode, formerly pro-
ID
tected sectors can be programmed or erased by
selecting the sector addresses. Once V is removed
ID
from the RESET# pin, all the previously protected
sectors are protected again. Figure 2, on page 13
shows the algorithm, and Figure 22, on page 33 shows
the timing diagrams, for this feature.
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
April 13, 2005 Rev. A Amend. +1
Am29SL400D
11
AMD [ AMD ]
