quence should be reinitiated once the device has reset
to reading array data, to ensure data integrity.
START
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 suc-
cessful. However, a succeeding read will show that the
data is still “0”. Only erase operations can convert a “0”
to a “1”.
Write Program
Command Sequence
Data Poll
from System
Unlock Bypass Command Sequence
Embedded
Program
algorithm
in progress
The unlock bypass feature allows the system to pro-
gram bytes to the device faster than using the standard
program command sequence. The unlock bypass com-
mand 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 en-
ters the unlock bypass mode. A two-cycle unlock by-
pass program command sequence is all that is required
to program in this mode. The first cycle in this se-
quence contains the unlock bypass program com-
mand, 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 program-
ming time. Table 8 shows the requirements for the com-
mand sequence.
Verify Data?
Yes
No
No
Increment Address
Last Address?
Yes
Programming
Completed
During the unlock bypass mode, only the Unlock By-
pass Program and Unlock Bypass Reset commands
are valid. To exit the unlock bypass mode, the system
must issue the two-cycle unlock bypass reset com-
mand sequence. The first cycle must contain the data
90h; the second cycle the data 00h. Addresses are
don’t cares for both cycles. The device then returns to
reading array data.
Note: See Table 8 for program command sequence.
Figure 3. Program Operation
Chip Erase Command Sequence
Figure 3 illustrates the algorithm for the program oper-
ation. See the Erase/Program Operations table in “AC
Characteristics” for parameters, and to Figure 15 for
timing diagrams
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 algo-
rithm 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 con-
trols or timings during these operations. Table 8 shows
the address and data requirements for the chip erase
command sequence.
Any commands written to the chip during the Embed-
ded Erase algorithm are ignored. Note that a hardware
reset during the chip erase operation immediately ter-
minates the operation. The Chip Erase command se-
quence should be reinitiated once the device has
returned to reading array data, to ensure data integrity.
22
Am29LV017D
AMD [ AMD ]
