EN29LV400A
operation in the Erase Suspend mode, the system may once again read array data with the same
exception.
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 EN29LV400A 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 CE# or
WE#, whichever is last; data is latched on the rising edge of CE# or WE#, whichever is first.
Programming status may be checked by sampling data on DQ7 (DATA# polling) or on DQ6 (toggle
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.
This Data Sheet may be revised by subsequent versions
or modifications due to changes in technical specifications.
©2005 Eon Silicon Solution, Inc., www.essi.com.tw
12
Rev. A, Issue Date: 2005/01/07
EON [ EON SILICON SOLUTION INC. ]
