MX29LV800BT Macronix, MX29LV800BT Datasheet - Page 19

• Manufacturer Part Number: MX29LV800BT
• Description: 8M-Bit CMOS Single Voltage 3V Only Flash Memory
• Manufacturer: Macronix

Q3
Sector Erase Timer
After the completion of the initial sector erase command
sequence, the sector erase time-out will begin. Q3 will
remain low until the time-out is complete. DATA# polling
and Toggle Bit are valid after the initial sector erase com-
mand sequence.
If DATA# polling or the Toggle Bit indicates the device
has been written with a valid erase command, Q3 may
be used to determine if the sector erase timer window is
still open. If Q3 is high ("1") the internally controlled
erase cycle has begun; attempts to write subsequent
commands to the device will be ignored until the erase
operation is completed as indicated by DATA# polling or
Toggle Bit. If Q3 is low ("0"), the device will accept
additional sector erase commands. To insure the com-
mand has been accepted, the system software should
check the status of Q3 prior to and following each sub-
sequent sector erase command. If Q3 were high on the
second status check, the command may not have been
accepted.
DATA PROTECTION
The MX29LV800BT/BB 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.
WRITE PULSE "GLITCH" PROTECTION
Noise pulses of less than 5ns(typical) on CE# or WE#
will not initiate a write cycle.
LOGICAL INHIBIT
Writing is inhibited by holding any one of OE# = VIL,
CE# = VIH or WE# = VIH. To initiate a write cycle CE#
and WE# must be a logical zero while OE# is a logical
one.
P/N:PM1062
19
POW
In order to reduce power switching effect, each device
should have a 0.1uF ceramic capacitor connected be-
tween its VCC and GND.
POWER-UP SEQUENCE
The MX29LV800BT/BB powers up in the Read only mode.
In addition, the memory contents may only be altered
after successful completion of the predefined command
sequences.
TEMPORARY SECTOR UNPROTECTED
This feature allows temporary unprotected of previously
protected sector to change data in-system. The Tempo-
rary Sector Unprotected mode is activated by setting
the RESET# pin to VID(11.5V-12.5V). During this mode,
formerly protected sectors can be programmed or erased
as un-protected sector. Once VID is remove from the
RESET# pin, all the previously protected sectors are
protected again.
SECTOR PROTECTION
The MX29LV800BT/BB features hardware sector pro-
tection. This feature will disable both program and erase
operations for these sectors protected. To activate this
mode, the programming equipment must force VID on
address pin A9 and OE# (suggest VID = 12V). Pro-
gramming of the protection circuitry begins on the falling
edge of the WE# pulse and is terminated on the rising
edge. Please refer to sector protect algorithm and wave-
form.
To verify programming of the protection circuitry, the pro-
gramming equipment must force VID on address pin A9
( with CE# and OE# at VIL and WE# at VIH). When
A1=VIH, A0=VIL, A6=VIL, it will produce a logical "1"
code at device output Q0 for a protected sector. Other-
wise the device will produce 00H for the unprotected
sector. In this mode, the addresses, except for A1, are
don't care. Address locations with A1 = VIL are reserved
to read manufacturer and device codes. (Read Silicon
ID)
It is also possible to determine if the sector is protected
in the system by writing a Read Silicon ID command.
MX29LV800BT/BB
ER SUPPLY DECOUPLING
REV. 1.3, DEC. 20, 2004