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EN29F800 Datasheet, PDF (8/38 Pages) List of Unclassifed Manufacturers – 8 Megabit (1024K x 8-bit / 512K x 16-bit) Flash Memory Boot Sector Flash Memory, CMOS 5.0 Volt-only
EN29F800
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
VID. See “Command Definitions” for details on using the autoselect mode.
Write Mode
Programming is a four-bus-cycle operation. The program command sequence is initiated by writing two
unlock write cycles, followed by the program set-up command. The program address and data are written
next, which in turn initiate the Embedded Program algorithm. The system is not required to provide further
controls or timings. The device automatically provides internally generated program pulses and verifies
the programmed cell margin. The Command Definitions in Table 5 show the address and data
requirements for the byte program command sequence.
When the Embedded Program algorithm is complete, the device then returns to reading array data and
addresses are no longer latched. The system can determine the status of the program operation by using
DQ7 or DQ6. See “Write Operation Status” for information on these status bits.
Any commands written to the device during the Embedded Program Algorithm are ignored.
Programming is allowed in any sequence and across sector boundaries. A bit cannot be programmed
from a “0” back to a “1”. Attempting to do so may halt the operation and set DQ5 to “1”, or cause the
Data# Polling algorithm to indicate the operation was successful. However, a succeeding read will show
that the data is still “0”. Only erase operations can convert a “0” to a “1”.
Sector Protection/Unprotection
The hardware sector protection feature disables both program and erase operations in any sector. The
hardware sector unprotection feature re-enables both program and erase operations in previously
protected sectors.
Sector protection/unprotection must be implemented using programming equipment. The procedure re-
quires a high voltage (VID) on address pin A9 and the control pins. Details on this method are provided in
a supplement, which can be obtained by contacting a representative of Eon Silicon Devices, Inc.
Temporary Sector Unprotect
This feature allows temporary unprotection of previously protected
sector groups to change data while in-system. The Sector Unprotect
mode is activated by setting the RESET# pin to VID. During this mode,
formerly protected sector groups can be programmed or erased by
simply selecting the sectgor addresses. Once is removed from the
RESET# pin, all the previously protected sector are protected again.
See accompanying figure and timing diagrams for more details.
Notes:
1. All protected sectors unprotected.
2. Previously protected sectors protected
again.
Start
Reset#=VID (note 1)
Perform Erase or Program
Operations
Reset#=VIH
Temporary Sector
Unprotect Completed (note 2)
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Rev. E, Issue Date: 2001/07/05
Tel: 408-235-8680
Fax: 408-235-8685