MX29F040C
Q5
Exceeded Timing Limits
Q5 will indicate if the program or erase time has exceeded
the specified limits (internal pulse count). Under these
conditions Q5 will produce a "1". This time-out condition
indicates that the program or erase cycle was not suc-
cessfully completed. Data# Polling and Toggle Bit are
the only operating functions of the device under this con-
dition.
If this time-out condition occurs during sector erase op-
eration, it specifies that a particular sector is bad and it
may not be reused. However, other sectors are still func-
tional and may be used for the program or erase opera-
tion. The device must be reset to use other sectors.
Write the Reset command sequence to the device, and
then execute program or erase command sequence. This
allows the system to continue to use the other active
sectors in the device.
If this time-out condition occurs during the chip erase
operation, it specifies that the entire chip is bad or com-
bination of sectors are bad.
If this time-out condition occurs during the byte program-
ming operation, it specifies that the entire sector con-
taining that byte is bad and this sector may not be re-
used, (other sectors are still functional and can be re-
used).
The time-out condition may also appear if a user tries to
program a non blank location without erasing. In this
case the device locks out and never completes the Au-
tomatic Algorithm operation. Hence, the system never
reads a valid data on Q7 bit and Q6 never stops toggling.
Once the Device has exceeded timing limits, the Q5 bit
will indicate a "1". Please note that this is not a device
failure condition since the device was incorrectly used.
several features to prevent inadvertent write cycles re-
sulting from VCC power-up and power-down transition or
system noise.
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 addi-
tional sector erase commands. To insure the command
has been accepted, the system software should check
the status of Q3 prior to and following each subsequent
sector erase command. If Q3 were high on the second
status check, the command may not have been accepted.
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.
DATA PROTECTION
The MX29F040C 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
POWER SUPPLY DECOUPLING
In order to reduce power switching effect, each device
should have a 0.1uF ceramic capacitor connected be-
tween its VCC and GND.
P/N:PM1201
REV. 1.0, DEC. 20, 2005
11
MCNIX [ MACRONIX INTERNATIONAL ]
