A29L800 AMIC Technology, A29L800 Datasheet - Page 14

• Manufacturer Part Number: A29L800
• Description: 1M X 8 Bit / 512K X 16 Bit CMOS 3.0 Volt-only/ Boot Sector Flash Memory
• Manufacturer: AMIC Technology

Unlock Bypass Command Sequence
The unlock bypass feature allows the system to program
bytes or words to the device faster than using the standard
program command sequence. The unlock bypass command
sequence is initiated by first writing two unlock cycles. This is
followed by a third write cycle containing the unlock bypass
command, 20h. The device then enters the unlock bypass
mode. A two-cycle unlock bypass program command
sequence is all that is required to program in this mode. The
first cycle in this sequence contains the unlock bypass
program command, A0h; the second cycle contains the
program address and data. Additional data is programmed in
the same manner. This mode dispenses with the initial two
unlock cycles required in the standard program command
sequence, resulting in faster total programming time. Table 5
shows the requirements for the command sequence.
PRELIMINARY
Note : See the appropriate Command Definitions table for
Increment Address
program command sequence.
algorithm in
Embedded
Program
progress
Figure 3. Program Operation
(September, 2002, Version 0.2)
Last Address ?
Write Program
Programming
Verify Data ?
from System
Completed
Command
Sequence
Data Poll
START
Yes
Yes
No
14
During the unlock bypass mode, only the Unlock Bypass
Program and Unlock Bypass Reset commands are valid. To
exit the unlock bypass mode, the system must issue the two-
cycle unlock bypass reset command sequence. The first cycle
must contain the data 90h; the second cycle the data 00h.
Addresses are don’t care for both cycle. The device returns to
reading array data.
Figure 3 illustrates the algorithm for the program operation.
See the Erase/Program Operations in “AC Characteristics” for
parameters, and to Program Operation Timings for timing
diagrams.
Chip Erase Command Sequence
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 chip erase command, which in
turn invokes the Embedded Erase algorithm. The device does
not 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
Erase algorithm are ignored. The system can determine the
status of the erase operation by using I/O
"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.
Figure 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.
Sector Erase Command Sequence
Sector erase is a six-bus-cycle operation. The sector 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 address of the sector to be
erased, and the sector erase command. The Command
Definitions table shows the address and data requirements for
the sector erase command sequence.
The device does not require the system to preprogram the
memory prior to erase. The Embedded Erase algorithm
automatically programs and verifies the sector for an all zero
data pattern prior to electrical erase. The system is not
required to provide any controls or timings during these
operations.
After the command sequence is written, a sector erase time-
out of 50 s begins. During the time-out period, additional
sector addresses and sector erase commands may be written.
Loading the sector erase buffer may be done in any
sequence, and the number of sectors may be from one sector
to all sectors. The time between these additional cycles must
be less than 50 s, otherwise the last address and command
might not be accepted, and erasure may begin. It is
recommended that processor interrupts be disabled during
this time to ensure all commands are accepted. The interrupts
AMIC Technology, Inc.
A29L800 Series
7
, I/O
6
, or I/O
2
. See