MX29LV320CB Macronix International, MX29LV320CB Datasheet - Page 14

• Manufacturer Part Number: MX29LV320CB
• Description: 32M-BIT [4M x 8 / 2M x 16] SINGLE VOLTAGE 3V ONLY FLASH MEMORY
• Manufacturer: Macronix International

used to replace devices that are factory locked.
The system accesses the Security Sector through a com-
mand sequence (see "Enter Security Sector/Exit Secu-
rity Sector Command Sequence"). After the system has
written the Enter Security Sector command se-quence,
it may read the Security Sector by using the ad-dresses
normally occupied by the boot sectors. This mode of op-
eration continues until the system issues the Exit Secu-
rity 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.
Factory Locked: Security Sector Programmed and
Protected at the Factory
In a factory locked device, the Security Sector is pro-
tected when the device is shipped from the factory. The
Security Sector cannot be modified in any way. The de-
vice is available preprogrammed with one of the follow-
ing:
A random, secure ESN only.
In devices that have an ESN, a Bottom Boot device will
have the 16-byte (8-word) ESN in the lowest address-
able memory area starting at 00000h and ending at
0000Fh (00007h). In the Top Boot device the starting
address of the ESN will be at the bottom of the lowest 8
Kbyte (4 Kword) boot sector starting at 3F0000h
(1F8000h) and ending at 3F000Fh (1F8007h).
Customer Lockable: Security Sector NOT Pro-
grammed or Protected at the Factory
If the security feature is not required, the Security Sec-
tor can be treated as an additional Flash memory space,
expanding the size of the available Flash array by 64
Kbytes (32 Kwords). The Security Sector can be read,
programmed, and erased as often as required. The Se-
curity Sector area can be protected using one of the
following procedures:
Write the three-cycle Enter Security Region command
sequence, and then follow the in-system sector group
protect algorithm as shown in Figure 14, except that
RESET# may be at either VIH or V
tem protection of the without raising any device pin to a
high voltage. Note that this method is only applicable to
P/N:PM1188
ID
. This allows in-sys-
14
MX29LV320C T/B
the Security Sector.
Write the three-cycle Enter Security Region command
sequence, and then use the alternate method of sector
protection described in the "Sector/Sector Block Protec-
tion and Unprotection section.
Once the Security Sector is locked and verified, the sys-
tem must write the Exit Security Sector Region com-
mand sequence to return to reading and writing the re-
mainder of the array.
The Security Sector protection must be used with cau-
tion since, once protected, there is no procedure avail-
able for unprotecting the Security Sector area and none
of the bits in the Security Sector memory space can be
modified in any way.
DATA PROTECTION
The MX29LV320C T/B 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.
LOW VCC WRITE INHIBIT
When VCC is less than VLKO the device does not ac-
cept any write cycles. This protects data during VCC
power-up and power-down. The command register and
all internal program/erase circuits are disabled, and the
device resets. Subsequent writes are ignored until VCC
is greater than VLKO. The system must provide the proper
signals to the control pins to prevent unintentional write
when VCC is greater than VLKO.
WRITE PULSE "GLITCH" PROTECTION
Noise pulses of less than 5ns (typical) on OE#, CE# or
WE# will not initiate a write cycle.
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REV. 1.0, AUG. 02, 2005