rithm. Upon executing the algorithm, the system is not
required to provide further controls or timings. The de-
vice will automatically provide adequate internally gen-
erated program pulses and verify the programmed cell
margin.
then followed by the sector erase command. The sector
address (any address location within the desired sec-
tor) is latched on the falling edge of WE, while the com-
mand (30H) is latched on the rising edge of WE. After
a time-out of 50 µs from the rising edge of the last sec-
tor erase command, the sector erase operation will
begin.
This automatic programming operation is completed
when the data on DQ7 (also used as Data Polling) is
equivalent to the data written to this bit at which time
the device returns to the read mode and addresses are
no longer latched (see Table 6, Write Operation Sta-
tus). Therefore, the device requires that a valid address
to the device be supplied by the system at this particu-
lar instance of time for Data Polling operations. Data
Polling must be performed at the memory location
which is being programmed.
Multiple sectors may be erased sequentially by writing
the six bus cycle operations as described above. This
sequence is followed with writes of the Sector Erase
command to addresses in other sectors desired to be
concurrently erased. The time between writes must be
less than 50 µs otherwise that command will not be ac-
cepted and erasure will start. It is recommended that
processor interrupts be disabled during this time to
guarantee this condition. The interrupts can be re-en-
abled after the last Sector Erase command is written. A
time-out of 50 µs from the rising edge of the last WE will
initiate the execution of the Sector Erase command(s).
If another falling edge of the WE occurs within the 50
µs time-out window the timer is reset. (Monitor DQ3 to
determine if the sector erase timer window is still open,
see section DQ3, Sector Erase Timer.) Any command
other than Sector Erase or Erase Suspend during this
period will reset the device to the read mode, ignoring
the previous command string. In that case, restart the
erase on those sectors and allow them to com-
plete.(Refer to the Write Operation Status section for
DQ3, Sector Erase Timer, operation.) Loading the sec-
tor erase buffer may be done in any sequence and with
any number of sectors (0 to 31).
Any commands written to the chip during the Embed-
ded Program Algorithm will be ignored. If a hardware
reset occurs during the programming operation, the
data at that particular location will be corrupted.
Programming is allowed in any sequence and across
sector boundaries. Beware that a data “0” cannot be
programmed back to a “1”. Attempting to do so may ei-
ther hang up the device or result in an apparent suc-
cess according to the data polling algorithm but a read
from reset/read mode will show that the data is still “0”.
Only erase operations can convert “0”s to “1”s.
Figure 1 illustrates the Embedded Programming Algo-
rithm using typical command strings and bus
operations.
Chip Erase
Sector erase does not require the user to program the
device prior to erase. The device automatically pro-
grams all memory locations in the sector(s) to be
erased prior to electrical erase. When erasing a sector
or sectors the remaining unselected sectors are not af-
fected. The system is not required to provide any con-
trols or timings during these operations.
Chip erase is a six bus cycle operation. There are two
“unlock” write cycles. These are followed by writing the
“set-up” command. Two more “unlock” write cycles are
then followed by the chip erase command.
Chip erase does not require the user to program the
device prior to erase. Upon executing the Embedded
Erase Algorithm command sequence the device will
automatically program and verify the entire memory 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.
The automatic sector erase begins after the 50 µs time
out from the rising edge of the WE pulse for the last
sector erase command pulse and terminates when the
data on DQ7, Data Polling, is “1” (see Write Operation
Status section) at which time the device returns to the
read mode. Data Polling must be performed at an ad-
dress within any of the sectors being erased.
The automatic erase begins on the rising edge of the
last WE pulse in the command sequence and termi-
nates when the data on DQ7 is “1” (see Write Opera-
tion Status section) at which time the device returns to
read mode.
Figure 2 illustrates the Embedded Erase Algorithm
using typical command strings and bus operations.
Erase Suspend
Figure 2 illustrates the Embedded Erase Algorithm
using typical command strings and bus operations.
The Erase Suspend command allows the user to inter-
rupt a Sector Erase operation and then perform data
reads or programs to a sector not being erased. This
command is applicable ONLY during the Sector Erase
operation which includes the time-out period for sector
erase. The Erase Suspend command will be ignored if
written during the Chip Erase operation or Embedded
Sector Erase
Sector erase is a six bus cycle operation. There are two
“unlock” write cycles. These are followed by writing the
“set-up” command. Two more “unlock” write cycles are
Am29F016
13
AMD [ AMD ]
