P R E L I M I N A R Y
Table 4. In addition, when verifying sector protection,
Autoselect Mode
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.
The autoselect mode provides manufacturer and de-
vice 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. This method
does not require VID. See “Command Definitions” for
details on using the autoselect mode.
When using programming equipment, the autoselect
mode requires VID (11.5 V to 12.5 V) on address pin
A9. Address pins A6, A1, and A0 must be as shown in
Table 4. Am29LV400 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
L
X
L
L
X
01h
B9h
ID
Device ID:
Am29LV400
(Top Boot Block)
Word
Byte
22h
X
X
V
X
L
L
X
L
L
H
ID
L
L
L
L
H
H
X
B9h
BAh
Device ID:
Am29LV400
(Bottom Boot
Block)
Word
22h
X
X
X
V
V
X
X
X
X
H
L
ID
Byte
L
L
H
X
BAh
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 pro-
gram and erase operations in previously protected
sectors.
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 RE-
SET# pin to VID. During this mode, formerly protected
sectors can be programmed or erased by selecting the
sector addresses. Once VID is removed from the RE-
SET# pin, all the previously protected sectors are
protected again. Figure 1 shows the algorithm, and
Figure 21 shows the timing diagrams, for this feature.
Sector protection/unprotection is implemented using
programming equipment, and requires VID on address
pin A9 and OE#. Publication number 20873 contains
further details; contact an AMD representative to re-
quest 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
11
Am29LV400
CYPRESS [ CYPRESS ]
