EN29LV400
The Reset command must be issued to re-enable the device for reading array data if DQ5 goes high, or
while in the autoselect mode. See next section for details on Reset.
Reset Command
Writing the reset command to the device resets the device to reading array data. Address bits are don’t-
care for this command.
The reset command may be written between the sequence cycles in an erase command sequence before
erasing begins. This resets the device to reading array data. Once erasure begins, however, the device
ignores reset commands until the operation is complete. The reset command may be written between the
sequence cycles in a program command sequence before programming begins. This resets the device to
reading array data (also applies to programming in Erase Suspend mode). Once programming begins,
however, the device ignores reset commands until the operation is complete.
The reset command may be written between the sequence cycles in an autoselect command sequence.
Once in the autoselect mode, the reset command must be written to return to reading array data (also
applies to autoselect during Erase Suspend).
If DQ5 goes high during a program or erase operation, writing the reset command returns the device to
reading array data (also applies during Erase Suspend).
Autoselect Command Sequence
The autoselect command sequence allows the host system to access the manufacturer and devices
codes, and determine whether or not a sector is protected. The Command Definitions table shows the
address and data requirements. This is an alternative to the method that requires VID on address bit A9
and is intended for PROM programmers.
Two unlock cycles followed by the autoselect command initiate the autoselect command sequence.
Autoselect mode is then entered and the system may read at addresses shown in Table 4 any number of
times, without needing another command sequence.
The system must write the reset command to exit the autoselect mode and return to reading array data.
Word / Byte Programming Command
The device may be programmed by byte or by word, depending on the state of the Byte# Pin.
Programming the EN29LV400 is performed by using a four bus-cycle operation (two unlock write
cycles followed by the Program Setup command and Program Data Write cycle). When the program
command is executed, no additional CPU controls or timings are necessary. An internal timer
terminates the program operation automatically. Address is latched on the falling edge of
or
CE
, whichever is last; data is latched on the rising edge of
or
, whichever is first.
W E
CE
W E
Programming status may be checked by sampling data on DQ7 (
polling) or on DQ6 (toggle
DATA
bit). ). When the program operation is successfully completed, the device returns to read mode and
the user can read the data programmed to the device at that address. Note that data can not be
programmed from a 0 to a 1. Only an erase operation can change a data from 0 to 1. When
programming time limit is exceeded, DQ5 will produce a logical “1” and a Reset command can
return the device to Read mode.
Unlock Bypass
To speed up programming operation, the Unlock Bypass Command may be used. Once this feature
is activated, the shorter two cycle Unlock Bypass Program command can be used instead of the
This Data Sheet may be revised by subsequent versions
or modifications due to changes in technical specifications.
©2004 Eon Silicon Solution, Inc., www.essi.com.tw
Rev. C, Issue Date: 2004/03/18
12
ESMT [ ELITE SEMICONDUCTOR MEMORY TECHNOLOGY INC. ]
