MX29LV400T/B
the Flash memory.
If RESET is asserted during a program or erase
operation, the RY/BY pin remains a "0" (busy) until the
internal reset operation is complete, which requires a
time of tREADY (during Embedded Algorithms). The
sysytem can thus monitor RY/BY to determine whether
the reset operation is complete. If RESET is asserted
when a program or erase operation is commpleted within
a time of tREADY (not during Embedded Algorithms).
The system can read data tRH after the RESET pin
returns to VIH.
Refer to the AC Characteristics tables for RESET
parameters and to Figure 24 for the timing diagram.
SET-UP AUTOMATIC CHIP/SECTOR ERASE
COMMANDS
Chip erase is a six-bus cycle operation. There are two
"unlock" write cycles. These are followed by writing the
"set-up" command 80H. Two more "unlock" write cy-
cles are then followed by the chip erase command 10H
or sector erase command 30H.
The Automatic Chip Erase does not require the device
to be entirely pre-programmed prior to executing the Au-
tomatic Chip Erase. Upon executing the Automatic Chip
Erase, the device will automatically program and verify
the entire memory for an all-zero data pattern. When the
device is automatically verified to contain an all-zero
pattern, a self-timed chip erase and verify begin. The
erase and verify operations are completed when the data
on Q7 is "1" at which time the device returns to the
Read mode. The system is not required to provide any
control or timing during these operations.
When using the Automatic Chip Erase algorithm, note
that the erase automatically terminates when adequate
erase margin has been achieved for the memory array(no
erase verification command is required).
If the Erase operation was unsuccessful, the data on
Q5 is "1"(see Table 7), indicating the erase operation
exceed internal timing limit.
The automatic erase begins on the rising edge of the
last WE or CE pulse, whichever happens first in the
command sequence and terminates when the data on
Q7 is "1" at which time the device returns to the Read
mode, or the data on Q6 stops toggling for two consecu-
tive read cycles at which time the device returns to the
Read mode.
READ/RESET COMMAND
The read or reset operation is initiated by writing the
read/reset command sequence into the command reg-
ister. Microprocessor read cycles retrieve array data.
The device remains enabled for reads until the command
register contents are altered.
If program-fail or erase-fail happen, the write of F0H will
reset the device to abort the operation. A valid com-
mand must then be written to place the device in the
desired state.
SILICON-ID READ COMMAND
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(VID). However, multiplexing high voltage
onto address lines is not generally desired system de-
sign practice.
The MX29LV400T/B contains a Silicon-ID-Read opera-
tion to supple traditional PROM programming methodol-
ogy. The operation is initiated by writing the read silicon
ID command sequence into the command register. Fol-
lowing the command write, a read cycle with A1=VIL,
A0=VIL retrieves the manufacturer code of C2H/00C2H.
A read cycle with A1=VIL, A0=VIH returns the device
code of B9H/22B9H for MX29LV400T, BAH/22BAH for
MX29LV400B.
P/N:PM0710
REV. 1.4, NOV. 23, 2001
10
MCNIX [ MACRONIX INTERNATIONAL ]
