9

3704BX–DFLASH–11/2012

AT25BCM512B [Preliminary]

Figure 8-1.

Byte Program

Figure 8-2.

Page Program

8.2

Block Erase

A block of 4 or 32 Kbytes can be erased (all bits set to the logical “1” state) in a single operation

by using one of three different opcodes for the Block Erase command. An opcode of 20h is used

for a 4-Kbyte erase, and an opcode of 52h or D8h is used for a 32-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 Register 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- or 32-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

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 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 deasserted, 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 memory is in the protected 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.

SCK

CS

SI

SO

MSB

MSB

23

1

0

00000010

67

5

410 11

9

812

39

37 38

33

36

35

34

31 32

29 30

OPCODE

HIGH-IMPEDANCE

AAAA

AAA

A

A

MSB

DDDDDDD

D

ADDRESS BITS A23-A0

DATA IN

SCK

CS

SI

SO

MSB

MSB

23

1

0

00000010

67

5

49

839

37 38

33

36

35

34

31 32

29 30

OPCODE

HIGH-IMPEDANCE

AA

AAA

A

MSB

DDDDDDD

D

ADDRESS BITS A23-A0

DATA IN BYTE 1

MSB

DDDDDDD

D

DATA IN BYTE n