en29lv040a-45rtip Eon Silicon Solution Inc., en29lv040a-45rtip Datasheet - Page 10

• Manufacturer Part Number: en29lv040a-45rtip
• Description: 4 Megabit 512k X 8-bit Uniform Sector Cmos 3.0 Volt-only Flash Memory
• Manufacturer: Eon Silicon Solution Inc.

EN29LV040A
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.
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 V
on address bit A9
ID
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.
Programming Command
Programming the EN29LV040A 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
, whichever is last; data is latched on the rising edge of CE or
, whichever is first.
W E
W E
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.
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
normal four cycle Program Command to program the device. This mode is exited after issuing the
Unlock Bypass Reset Command. The device powers up with this feature disabled.
Chip Erase Command
Chip erase is a six-bus-cycle operation. The chip erase command sequence is initiated by writing two
unlock cycles, followed by a set-up command. Two additional unlock write cycles are then followed by the
not
chip erase command, which in turn invokes the Embedded Erase algorithm. The device does
require
the system to preprogram prior to erase. The Embedded Erase algorithm automatically preprograms and
verifies the entire memory for an all zero data pattern prior to electrical erase. The system is not required
to provide any controls or timings during these operations. The Command Definitions table shows the
address and data requirements for the chip erase command sequence.
Any commands written to the chip during the Embedded Chip Erase algorithm are ignored.
The system can determine the status of the erase operation by using DQ7, DQ6, or DQ2. See “Write
Operation Status” for information on these status bits. When the Embedded Erase algorithm is complete,
the device returns to reading array data and addresses are no longer latched.
Flowchart 4 illustrates the algorithm for the erase operation. See the Erase/Program Operations tables in
“AC Characteristics” for parameters, and to the Chip/Sector Erase Operation Timings for timing
waveforms.
This Data Sheet may be revised by subsequent versions
©2003 Eon Silicon Solution, Inc., www.essi.com.tw
10
or modifications due to changes in technical specifications.
Rev. B, Issue Date: 2007/01/05