Rainbow Electronics AT25DF041A - Manual (Page 11)

11
3668E–DFLASH–11/2012
AT25DF041A
device. Deasserting the CS pin will start the internally self-timed program operation, and the byte
of data will be programmed into the memory location specified by A23 - A0.
After the first byte has been successfully programmed, a second byte can be programmed by
simply reasserting the CS pin, clocking in the ADh or AFh opcode, and then clocking in the next
byte of data. When the CS pin is deasserted, the second byte of data will be programmed into
the next sequential memory location. The process would be repeated for any additional bytes.
There is no need to reissue the Write Enable command once the Sequential Program Mode has
been entered.
When the last desired byte has been programmed into the memory array, the Sequential
Program Mode operation can be terminated by reasserting the CS pin and sending the
Write Disable command to the device to reset the WEL bit in the Status Register back to the
logical “0” state.
If more than one byte of data is ever clocked in during each program cycle, then only the last
byte of data sent on the SI pin will be stored in the internal latches. The programming of each
byte is internally self-timed and should take place in a time of t
BP
. For each program cycle, a
complete byte of data must be clocked into the device before the CS pin is deasserted, and the
CS pin must be deasserted on even byte boundaries (multiples of eight bits); otherwise, the
device will abort the operation, the byte of data will not be programmed into the memory array,
and the WEL bit in the Status Register will be reset back to the logical “0” state.
If the address initially specified by A23 - A0 points to a memory location within a sector that is in
the protected state, then the Sequential Program Mode command will not be executed, and the
device will return to the idle state once the CS pin has been deasserted. The WEL bit in the Sta-
tus Register will also be reset back to the logical “0” state.
There is no address wrapping when using the Sequential Program Mode. Therefore, when the
last byte (07FFFFh) of the memory array has been programmed, the device will automatically
exit the Sequential Program mode and reset the WEL bit in the Status Register back to the logi-
cal “0” state. In addition, the Sequential Program mode will not automatically skip over protected
sectors; therefore, once the highest unprotected memory location in a programming sequence
has been programmed, the device will automatically exit the Sequential Program mode and
reset the WEL bit in the Status Register. For example, if Sector 1 was protected and Sector 0
was currently being programmed, once the last byte of Sector 0 was programmed, the Sequen-
tial Program mode would automatically end. To continue programming with Sector 2, the
Sequential Program mode would have to be restarted by supplying the ADh or AFh opcode, the
three address bytes, and the first byte of Sector 2 to program.
While the device is programming a byte, the Status Register can be read and will indicate that
the device is busy. For faster throughput, it is recommended that the Status Register be polled at
the end of each program cycle rather than waiting the t
BP
time to determine if the byte has fin-
ished programming before starting the next Sequential Program mode cycle.
The device also incorporates an intelligent programming algorithm that can detect when a byte
location fails to program properly. If a programming error arises, it will be indicated by the EPE
bit in the Status Register.