am41pds3228d Meet Spansion Inc., am41pds3228d Datasheet - Page 22

• Manufacturer Part Number: am41pds3228d
• Description: 32 Mbit 2 M ? 16-bit Cmos 1.8 Volt-only, Simultaneous Operation Page Mode Flash Memory And 8 Mbit 1 M ? 8-bit/512 K ? 16-bit Static Ram Preliminary
• Manufacturer: Meet Spansion Inc.

SecSi (Secured Silicon) Sector Flash
Memory Region
The SecSi (Secured Silicon) Sector feature provides a
Flash memory region that enables permanent part
identification through an Electronic Serial Number
(ESN). The SecSi Sector is 64 KBytes in length, and
uses a SecSi Sector Indicator Bit (DQ7) to indicate
whether or not the SecSi Sector is locked when
shipped from the factory. This bit is permanently set at
the factory and cannot be changed, which prevents
cloning of a factory locked part. This ensures the secu-
rity of the ESN once the product is shipped to the field.
AMD offers the device with the SecSi Sector either
f a cto ry lo cked o r cu sto m e r lo cka b le. Th e f a c-
tory-locked version is always protected when shipped
from the factory, and has the SecSi (Secured Silicon)
Sector Indicator Bit permanently set to a “1.” The cus-
tomer-lockable version is shipped with the SecSi Sec-
tor unprotected, allowing customers to utilize that
sector in any manner they choose. The customer-lock-
able version also has the SecSi Sector Indicator Bit
permanently set to a “0.” Thus, the SecSi Sector Indi-
cator Bit prevents customer-lockable devices from
being used to replace devices that are factory locked.
The system accesses the SecSi Sector through a
command sequence (see “Enter SecSi Sector/Exit
SecSi Sector Command Sequence”). After the system
has written the Enter SecSi Sector command se-
quence, it may read the SecSi Sector by using the ad-
dresses normally occupied by the first sector (SA0).
This mode of operation continues until the system is-
sues the Exit SecSi Sector command sequence, or
until power is removed from the device. On power-up,
or following a hardware reset, the device reverts to
sending commands to the boot sectors instead of the
SecSi sector
Factory Locked: SecSi Sector Programmed and
Protected at the Factory
In a factory locked device, the SecSi Sector is pro-
tected when the device is shipped from the factory.
The SecSi Sector cannot be modified in any way. The
device is available preprogrammed with one of the
following:
In devices that have an ESN, a Bottom Boot device
will have the 16-byte ESN in the lowest addressable
memory area at addresses 000000h–000007h. In the
Top Boot device the starting address of the ESN will
be at the bottom of the lowest 8 Kbyte boot sector at
addresses 1F8000h–1F8007h.
May 13, 2002
A random, secure ESN only
Customer code through the ExpressFlash service
Both a random, secure ESN and customer code
through the ExpressFlash service.
P R E L I M I N A R Y
Am41PDS3228D
Customers may opt to have their code programmed by
AMD through the AMD ExpressFlash service. AMD
programs the customer’s code, with or without the ran-
dom ESN. The devices are then shipped from AMD’s
factory with the permanently locked. Contact an AMD
representative for details on using AMD’s Express-
Flash service.
Customer Lockable: SecSi Sector NOT
Programmed or Protected at the Factory
If the security feature is not required, the SecSi Sector
can be treated as an additional Flash memory space,
expanding the size of the available Flash array by 64
Kbytes. The SecSi Sector can be read, programmed,
and erased as often as required. The SecSi Sector area
can be protected using one of the following procedures:
Once the SecSi Sector is locked and verified, the sys-
te m m u st w rit e t h e E xit S e cSi S e c to r R e g io n
command sequence to return to reading and writing
the remainder of the array.
The SecSi Sector protection must be used with cau-
tion since, once protected, there is no procedure
available for unprotecting the SecSi Sector area and
none of the bits in the SecSi Sector memory space
can be modified in any way.
Hardware Data Protection
The command sequence requirement of unlock cycles
for programming or erasing provides data protection
against inadvertent writes (refer to Table 10 for com-
mand definitions). In addition, the following hardware
data protection measures prevent accidental erasure
or programming, which might otherwise be caused by
spurious system level signals during V
and power-down transitions, or from system noise.
Low V
When V
cept any write cycles. This protects data during V
power-up and power-down. The command register
and all internal program/erase circuits are disabled,
and the device resets to reading array data. Subse-
quent writes are ignored until V
Write the three-cycle Enter SecSi Sector Region
command sequence, and then follow the in-system
sector protect algorithm as shown in Figure 2, ex-
cept that RESET# may be at either V
allows in-system protection of the SecSi Sector
without raising any device pin to a high voltage.
Note that this method is only applicable to the SecSi
Sector.
Write the three-cycle Enter SecSi Sector Region
command sequence, and then use the alternate
method of sector protection described in the “Sec-
tor/Sector Block Protection and Unprotection” sec-
tion.
CC
CC
Write Inhibit
is less than V
LKO
, the device does not ac-
CC
is greater than V
IH
CC
or V
power-up
ID
. This
LKO
21
CC
.