MX29LA129ML Macronix International, MX29LA129ML Datasheet - Page 18

• Manufacturer Part Number: MX29LA129ML
• Description: 128M-BIT SINGLE VOLTAGE 3V ONLY UNIFORM SECTOR FLASH MEMORY
• Manufacturer: Macronix International

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DATA PROTECTION
The MX29LA129M H/L is designed to offer protection
against accidental erasure or programming caused by
spurious system level signals that may exist during power
transition. During power up the device automatically re-
sets the state machine in the Read mode. In addition,
with its control register architecture, alteration of the
memory contents only occurs after successful comple-
tion of specific command sequences. The device also
incorporates several features to prevent inadvertent write
cycles resulting from VCC power-up and power-down tran-
sition or system noise.
SECURED SILICON SECTOR
The MX29LA129M H/L features a OTP memory region
where the system may access through a command se-
quence to create a permanent part identification as so
called Electronic Serial Number (ESN) in the device.
Once this region is programmed, any further modifica-
tion on the region is impossible. The secured silicon sec-
tor is a 128 words in length, and uses a Secured Silicon
Sector Indicator Bit (Q7) to indicate whether or not the
Secured Silicon Sector is locked when shipped from the
factory. This bit is permanently set at the factory and
cannot be changed, which prevent duplication of a fac-
tory locked part. This ensures the security of the ESN
once the product is shipped to the field.
The MX29LA129M H/L offers the device with Secured
Silicon Sector either factory locked or customer lock-
able. The factory-locked version is always protected when
shipped from the factory , and has the Secured Silicon
Sector Indicator Bit permanently set to a "1". The cus-
tomer-lockable version is shipped with the Secured Sili-
con Sector unprotected, allowing customers to utilize that
sector in any form they prefer. The customer-lockable
version has the secured sector Indicator Bit permanently
set to a "0". Therefore, the Secured Silicon Sector Indi-
cator Bit prevents customer, lockable device from being
used to replace devices that are factory locked.
The system access the Secured Silicon Sector through
a command sequence (refer to "Enter Secured Silicon/
Exit Secured Silicon Sector command Sequence). After
the system has written the Enter Secured Silicon Sector
command sequence, it may read the Secured Silicon
Sector by using the address normally occupied by the
first sector SA0. Once entry the Secured Silicon Sector
the operation of boot sectors is disabled but the operation
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MX29LA129M H/L
of main sectors is as normally. This mode of operation
continues until the system issues the Exit Secured Sili-
con Sector command sequence, or until power is removed
from the device. On power-up, or following a hardware
reset, the device reverts to sending command to sector
SA0.
FACTORY LOCKED:Secured Silicon Sector
Programmed and Protected At the Factory
In device with an ESN, the Secured Silicon Sector is
protected when the device is shipped from the factory.
The Secured Silicon Sector cannot be modified in any
way. A factory locked device has an 8-word random ESN
at address 000000h-000007h.
CUSTOMER LOCKABLE:Secured Silicon
Sector NOT Programmed or Protected At the
Factory
As an alternative to the factory-locked version, the device
may be ordered such that the customer may program
and protect the 128-word Secured Silicon Sector.
Programming and protecting the Secured Silicon Sector
must be used with caution since, once protected, there
is no procedure available for unprotected the Secured
Silicon Sector area and none of the bits in the Secured
Silicon Sector memory space can be modified in any
way.
The Secured Silicon Sector area can be protected using
one of the following procedures:
Write the three-cycle Enter Secured Silicon Sector Region
command sequence, and then follow the in-system
sector protect algorithm as shown in Figure 15, except
that RESET# may be at either VIH or VID. This allows in-
system protection of the Secured Silicon Sector without
raising any device pin to a high voltage. Note that method
is only applicable to the Secured Silicon Sector.
Secured Silicon
Sector address
range
000000h-000007h
000008h-00007Fh
ESN factory
Unavailable
locked
ESN
REV. 1.0, FEB. 27, 2006
Determined by
Customer
Customer
lockable