AM29F032B-120 AMD [Advanced Micro Devices], AM29F032B-120 Datasheet - Page 16

• Manufacturer Part Number: AM29F032B-120
• Description: 32 Megabit (4 M x 8-Bit) CMOS 5.0 Volt-only, Uniform Sector Flash Memory
• Manufacturer: AMD [Advanced Micro Devices]

Note: See Table 5 for program command sequence.
Sector Erase Command Sequence
Sector erase is a six bus cycle operation. The sector
erase command sequence is initiated by writing two un-
lock cycles, followed by a set-up command. Two addi-
tional 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 sec-
tor erase command sequence.
The device does not require the system to preprogram
the memory prior to erase. The Embedded Erase algo-
rithm 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 tim-
ings during these operations.
After the command sequence is written, a sector erase
time-out of 50 µs begins. During the time-out period,
additional sector addresses and sector erase com-
mands may be written. Loading the sector erase buffer
may be done in any sequence, and the number of sec-
tors may be from one sector to all sectors. The time be-
tween these additional cycles must be less than 50 µs,
Increment Address
Figure 2. Program Operation
in progress
Embedded
algorithm
Program
No
Command Sequence
Write Program
Last Address?
Programming
from System
Verify Data?
Completed
Data Poll
START
Yes
Yes
No
Am29F032B
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 can
be re-enabled after the last Sector Erase command is
written. If the time between additional sector erase
commands can be assumed to be less than 50 µs, the
system need not monitor DQ3. Any command other
than Sector Erase or Erase Suspend during the
time-out period resets the device to reading array
data. The system must rewrite the command sequence
and any additional sector addresses and commands.
The system can monitor DQ3 to determine if the sector
erase timer has timed out. (See the “DQ3: Sector Erase
Timer” section.) The time-out begins from the rising
edge of the final WE# pulse in the command sequence.
Once the sector erase operation has begun, only the
Erase Suspend command is valid. All other commands
are ignored. Note that a hardware reset during the
sector erase operation immediately terminates the op-
eration. The Sector Erase command sequence should
be reinitiated once the device has returned to reading
array data, to ensure data integrity.
When the Embedded Erase algorithm is complete, the
device returns to reading array data and addresses are
no longer latched. The system can determine the sta-
tus of the erase operation by using DQ7, DQ6, DQ2, or
RY/BY#. Refer to “The Erase Resume command is
valid only during the Erase Suspend mode.” for infor-
mation on these status bits.
Figure 3 illustrates the algorithm for the erase opera-
tion. Refer to the Erase/Program Operations tables in
the “AC Characteristics” section for parameters, and to
the Sector Erase Operations Timing diagram for timing
waveforms.
Erase Suspend/Erase Resume Commands
The Erase Suspend command allows the system to in-
terrupt a sector erase operation and then read data
from, or program data to, any sector not selected for
erasure. This command is valid only during the sector
erase operation, including the 50 µs time-out period
during the sector erase command sequence. The
Erase Suspend command is ignored if written during
the chip erase operation or Embedded Program algo-
rithm. Writing the Erase Suspend command during the
Sector Erase time-out immediately terminates the
time-out period and suspends the erase operation. Ad-
dresses are “don’t-cares” when writing the Erase Sus-
pend command.
When the Erase Suspend command is written during a
sector erase operation, the device requires a maximum
of 20 µs to suspend the erase operation. However,
when the Erase Suspend command is written during
the sector erase time-out, the device immediately ter-
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