MX29LV640BU Macronix International, MX29LV640BU Datasheet - Page 15

• Manufacturer Part Number: MX29LV640BU
• Description: 64M-BIT [4M x 16] CMOS EQUAL SECTOR FLASH MEMORY
• Manufacturer: Macronix International

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unprotected is completed to incorporate any changes in
the code. It is recommended to protect all sectors before
activating chip unprotect mode.
To activate this mode, the programming equipment must
force VID on control pin OE# and address pin A9. The
CE# pins must be set at VIL. Pins A6 must be set to
VIH. (see Table 2) Refer to chip unprotected algorithm
and waveform for the chip unprotected algorithm. The
unprotected mechanism begins on the falling edge of the
WE# pulse and is terminated on the rising edge.
MX29LV640BU also provides another method. Which re-
quires VID on the RESET# only. This method can be imple-
mented either in-system or via programming equipment.
This method uses standard microprocessor bus cycle
timing.
It is also possible to determine if the chip is unprotected
in the system by writing the Read Silicon ID command.
Performing a read operation with A1=VIH, it will produce
00H at data outputs (Q0-Q15) for an unprotected sector.
It is noted that all sectors are unprotected after the chip
unprotected algorithm is completed.
WRITE PROTECT (WP#)
This Write Protect function provides a hardware protec-
tion method on the first sector without using VID.
If the system asserts VIL on the WP# pin, the device
disable program and erase function in the first sector in-
dependently of whether those sectors were protected or
unprotect using the method described in "Sector Group
Protection and Unprotect".
If the system asserts VIH on the WP# pin, the device
reverts to whether the first sector was previously set to
be protected or unprotected using the method described
in "Sector Group Protection and Unprotect".
TEMPORARY SECTOR GROUP UNPROTECT
OPERATION
This feature allows temporary unprotect of previously pro-
tected sector to change data in-system. The Temporary
Sector Unprotect mode is activated by setting the RE-
SET# pin to VID(11.5V-12.5V). During this mode, for-
merly protected sectors can be programmed or erased
as unprotected sector. Once VID is remove from the RE-
P/N:PM1081
15
SET# pin, all the previously protected sectors are pro-
tected again.
SILICON ID READ OPERATION
Flash memories are intended for use in applications where
the local CPU alters memory contents. As such, manu-
facturer and device codes must be accessible while the
device resides in the target system. PROM program-
mers typically access signature codes by raising A9 to
a high voltage. However, multiplexing high voltage onto
address lines is not generally desired system design prac-
tice.
MX29LV640BU provides hardware method to access the
silicon ID read operation. Which method requires VID on
A9 pin, VIL on CE#, OE#, A6, and A1 pins. Which apply
VIL on A0 pin, the device will output MXIC's manufac-
ture code of C2H. Which apply VIH on A0 pin, the device
will output MX29LV640BU device code of 22D7H.
VERIFY SECTOR GROUP PROTECT STATUS
OPERATION
MX29LV640BU provides hardware method for sector group
protect status verify. Which method requires VID on A9
pin, VIH on WE# and A1 pins, VIL on CE#, OE#, A6, and
A0 pins, and sector address on A16 to A21 pins. Which
the identified sector is protected, the device will output
01H. Which the identified sector is not protect, the device
will output 00H.
DATA PROTECTION
The MX29LV640BU is designed to offer protection against
accidental erasure or programming caused by spurious
system level signals that may exist during power transi-
tion. During power up the device automatically resets
the state machine in the Read mode. In addition, with its
control register architecture, alteration of the memory
contents only occurs after successful completion of spe-
cific command sequences. The device also incorporates
several features to prevent inadvertent write cycles re-
sulting from VCC power-up and power-down transition or
system noise.
MX29LV640BU
REV. 1.0, MAR. 08, 2005