This Data Sheet may be revised by subsequent versions ©2003 Eon Silicon Solution, Inc., www.essi.com.tw
or modifications due to changes in technical specifications.
6
EN29F040A
Rev. B, Issue Date: 2004/04/01
USER MODE DEFINITIONS
Standby Mode
The EN29F040A has a CMOS-compatible standby mode, which reduces the
current to
<
1µA
(typical). It is placed in CMOS-compatible standby when the
CE
pin is at V
CC
±
0.5. The device
also has a TTL-compatible standby mode, which reduces the maximum V
CC
current to < 1mA. It is
placed in TTL-compatible standby when the
CE
pin is at V
IH
. When in standby modes, the outputs
are in a high-impedance state independent of the
OE
input.
Read Mode
The device is automatically set to reading array data after device power-up. No commands are
required to retrieve data. The device is also ready to read array data after completing an Embedded
Program or Embedded Erase algorithm.
After the device accepts an Erase Suspend command, the device enters the Erase Suspend mode.
The system can read array data using the standard read timings, except that if it reads at an address
within erase-suspended sectors, the device outputs status data. After completing a programming
operation in the Erase Suspend mode, the system may once again read array data with the same
exception. See “Erase Suspend/Erase Resume Commands” for more information on this mode.
The system must issue the reset command to re-enable the device for reading array data if DQ5
goes high, or while in the autoselect mode. See “Reset Command” section.
See also “Requirements for Reading Array Data” in the “Device Bus Operations” section for more
information. The Read Operations table provides the read parameters, and Read Operation Timings
diagram shows the timing diagram.
Output Disable Mode
When the
OE
pin is at a logic high level (V
IH
), the output from the EN29F040A is disabled. The
output pins are placed in a high impedance state.
Auto Select Identification Mode
The autoselect mode provides manufacturer and device identification, and sector protection
verification, through identifier codes output on DQ7–DQ0. This mode is primarily intended for
programming equipment to automatically match a device to be programmed with its corresponding
programming algorithm. However, the autoselect codes can also be accessed in-system through the
command register.
When using programming equipment, the autoselect mode requires V
ID
(10.5 V to 11.5 V) on
address pin A9. Address pins A6, A1, and A0 must be as shown in Autoselect Codes (High Voltage
Method) table. In addition, when verifying sector protection, the sector address must appear on the
appropriate highest order address bits. Refer to the corresponding Sector Address Tables. The
Command Definitions table shows the remaining address bits that are don’t care. When all
necessary bits have been set as required, the programming equipment may then read the
corresponding identifier code on DQ7–DQ0.
To access the autoselect codes in-system; the host system can issue the autoselect command via
the command register, as shown in the Command Definitions table. This method does not require
V
ID
. See “Command Definitions” for details on using the autoselect mode.
