AT25DF321A Datasheet, PDF (15/58 Pages) ATMEL Corporation – 32-Megabit 2.7-volt Minimum SPI Serial Flash Memory

AT25DF321A [Preliminary]
Figure 8-4. Dual-Input Page Program
CS
SCK
SI
SOI
0 1 2 3 4 5 6 7 8 9 10 11 12
29 30 31 32 33 34 35 36 37 38 39
OPCODE
ADDRESS BITS A23-A0
INPUT
INPUT
DATA BYTE 1 DATA BYTE 2
1 0 1 0 0 0 1 0AAAAAA
MSB
MSB
A A A D6 D4 D2 D0 D6 D4 D2 D0
HIGH-IMPEDANCE
D7 D5 D3 D1 D7 D5 D3 D1
MSB
MSB
INPUT
DATA BYTE n
D6 D4 D2 D0
D7 D5 D3 D1
MSB
8.3 Block Erase
A block of 4, 32, or 64 Kbytes can be erased (all bits set to the logical “1” state) in a single oper-
ation by using one of three different opcodes for the Block Erase command. An opcode of 20h is
used for a 4-Kbyte erase, an opcode of 52h is used for a 32-Kbyte erase, and an opcode of D8h
is used for a 64-Kbyte erase. Before a Block Erase command can be started, the Write Enable
command must have been previously issued to the device to set the WEL bit of the Status Reg-
ister to a logical “1” state.
To perform a Block Erase, the CS pin must first be asserted and the appropriate opcode (20h,
52h, or D8h) must be clocked into the device. After the opcode has been clocked in, the three
address bytes specifying an address within the 4-, 32-, or 64-Kbyte block to be erased must be
clocked in. Any additional data clocked into the device will be ignored. When the CS pin is deas-
serted, the device will erase the appropriate block. The erasing of the block is internally self-
timed and should take place in a time of t_BLKE.
Since the Block Erase command erases a region of bytes, the lower order address bits do not
need to be decoded by the device. Therefore, for a 4-Kbyte erase, address bits A11-A0 will be
ignored by the device and their values can be either a logical “1” or “0”. For a 32-Kbyte erase,
address bits A14-A0 will be ignored, and for a 64-Kbyte erase, address bits A15-A0 will be
ignored by the device. Despite the lower order address bits not being decoded by the device, the
complete three address bytes must still be clocked into the device before the CS pin is deas-
serted, and the CS pin must be deasserted on an even byte boundary (multiples of eight bits);
otherwise, the device will abort the operation and no erase operation will be performed.
If the address specified by A23-A0 points to a memory location within a sector that is in the pro-
tected or locked down state, then the Block Erase 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 Status Register will be reset back to the logical “0” state if the erase cycle
aborts due to an incomplete address being sent, the CS pin being deasserted on uneven byte
boundaries, or because a memory location within the region to be erased is protected or locked
down.
While the device is executing a successful erase cycle, the Status Register can be read and will
indicate that the device is busy. For faster throughput, it is recommended that the Status Regis-
ter be polled rather than waiting the t_BLKE time to determine if the device has finished erasing. At
some point before the erase cycle completes, the WEL bit in the Status Register will be reset
back to the logical “0” state.
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3686C–DFLASH–12/08