D A T A S H E E T
Table 4. Am29F400B 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
VID
X
X
L
X
X
L
L
X
01h
23h
Device ID:
Am29F400B
(Top Boot Block)
Word
Byte
Word
Byte
22h
X
X
VID
L
L
L
L
H
L
L
L
L
L
L
H
H
H
X
22h
X
23h
ABh
ABh
Device ID:
Am29F400B
(Bottom Boot Block)
X
X
X
VID
X
X
X
X
H
L
01h
(protected)
X
X
Sector Protection Verification
L
L
H
SA
VID
L
H
00h
(unprotected)
L = Logic Low = VIL, H = Logic High = VIH, SA = Sector Address, X = Don’t care.
rithm, and Figure 18 shows the timing diagrams, for this
feature.
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.
START
Sector protection/unprotection must be implemented
using programming equipment. The procedure
RESET# = VID
(Note 1)
requires a high voltage (V ) on address pin A9 and
ID
OE#. Details on this method are provided in a supple-
ment, publication number 20185. Contact an AMD
representative to obtain a copy of this document.
Perform Erase or
Program Operations
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.
RESET# = VIH
Temporary Sector
Unprotect Completed
(Note 2)
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
Notes:
1. All protected sectors unprotected.
2. All previously protected sectors are protected once
again.
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
from the RESET# pin, all the previously protected
sectors are protected again. Figure 1 shows the algo-
ID
Figure 1. Temporary Sector Unprotect Operation
November 11, 2009 21505E8
Am29F400B
11
CYPRESS [ CYPRESS ]
