参数资料
型号: AM29F400BT-90SE
厂商: ADVANCED MICRO DEVICES INC
元件分类: PROM
英文描述: 4 Megabit (512 K x 8-Bit/256 K x 16-Bit) CMOS 5.0 Volt-only Boot Sector Flash Memory
中文描述: 256K X 16 FLASH 5V PROM, 90 ns, PDSO44
封装: MO-180AA, SOP-44
文件页数: 10/37页
文件大小: 238K
代理商: AM29F400BT-90SE
10
Am29F400B
P R E L IM IN A R Y
Table 4.
Am29F400B Autoselect Codes (High Voltage Method)
L = Logic Low = V
IL
, H = Logic High = V
IH
, SA = Sector Address, X = Don’t care.
Sector Protection/Unprotection
The hardware sector protection feature disables both pro-
gram 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 must be implemented
using programming equipment. The procedure re-
quires a high voltage (V
ID
) on address pin A9 and OE#.
Details on this method are provided in a supplement,
publication number 20185. Contact an AMD represent-
ative to obtain a copy of this document.
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 “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 V
ID
. During this mode, formerly protected
sectors can be programmed or erased by selecting the
sector addresses. Once V
ID
is removed from the RE-
SET# pin, all the previously protected sectors are
protected again. Figure 1 shows the algorithm, and
Figure 18 shows the timing diagrams, for this feature.
Figure 1.
Temporary Sector Unprotect Operation
Hardware Data Protection
The command sequence requirement of unlock cycles
for programming or erasing provides data protection
against inadvertent writes (refer to Table 5 for com-
mand definitions). In addition, the following hardware
data protection measures prevent accidental erasure
or programming, which might otherwise be caused by
Description
Mode
CE#
OE#
WE#
A17
to
A12
A11
to
A10
A9
A8
to
A7
A6
A5
to
A2
A1
A0
DQ8
to
DQ15
DQ7
to
DQ0
Manufacturer ID
:
AMD
L
L
H
X
X
V
ID
X
L
X
L
L
X
01h
Device ID:
Am29F400B
(Top Boot Block)
Word
L
L
H
X
X
V
ID
X
L
X
L
H
22h
23h
Byte
L
L
H
X
23h
Device ID:
Am29F400B
(Bottom Boot Block)
Word
L
L
H
X
X
V
ID
X
L
X
L
H
22h
ABh
Byte
L
L
H
X
ABh
Sector Protection Verification
L
L
H
SA
X
V
ID
X
L
X
H
L
X
01h
(protected)
X
00h
(unprotected)
START
Perform Erase or
Program Operations
RESET# = V
IH
Temporary Sector
Unprotect Completed
(Note 2)
RESET# = V
ID
(Note 1)
Notes:
1. All protected sectors unprotected.
2. All previously protected sectors are protected once
again.
21505C-5
相关PDF资料
PDF描述
AM29F400BT-90SEB 4 Megabit (512 K x 8-Bit/256 K x 16-Bit) CMOS 5.0 Volt-only Boot Sector Flash Memory
AM29F400BT-90SI 4 Megabit (512 K x 8-Bit/256 K x 16-Bit) CMOS 5.0 Volt-only Boot Sector Flash Memory
Am29F400BT-90SIB 4 Megabit (512 K x 8-Bit/256 K x 16-Bit) CMOS 5.0 Volt-only Boot Sector Flash Memory
AM29F400BT-90SC0 4 Megabit (512 K x 8-Bit/256 K x 16-Bit) CMOS 5.0 Volt-only Boot Sector Flash Memory
AM29F400BT-90EC 4 Megabit (512 K x 8-Bit/256 K x 16-Bit) CMOS 5.0 Volt-only Boot Sector Flash Memory
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