AT45DB021D datasheet(25/52 Pages) ATMEL

25 / 52 page

3638F–DFLASH–4/08

AT45DB021D

13. “Power of 2” Binary Page Size Option

“Power of 2” binary page size Configuration Register is a user-programmable nonvolatile regis-

ter that allows the page size of the main memory to be configured for binary page size

(256 bytes) or the DataFlash standard page size (264 bytes). The “power of 2” page size is a

One-time Programmable (OTP) register and once the device is configured for “power of

2” page size, it cannot be reconfigured again. The devices are initially shipped with the page

size set to 264 bytes. The user has the option of ordering binary page size (256 bytes) devices

from the factory. For details, please refer to Section 26. ”Ordering Information” on page 47.

For the binary “power of 2” page size to become effective, the following steps must be followed:

Program the one-time programmable configuration resister using opcode sequence

3DH, 2AH, 80H and A6H (please see Section 13.1).

Power cycle the device (i.e. power down and power up again).

The page for the binary page size can now be programmed.

If the above steps are not followed to set the page size prior to page programming, incorrect

data during a read operation may be encountered.

13.1

Programming the Configuration Register

To program the Configuration Register for “power of 2” binary page size, the CS pin must first be

asserted as it would be with any other command. Once the CS pin has been asserted, the

appropriate 4-byte opcode sequence must be clocked into the device in the correct order. The

4-byte opcode sequence must start with 3DH and be followed by 2AH, 80H, and A6H. After the

last bit of the opcode sequence has been clocked in, the CS pin must be deasserted to initiate

the internally self-timed program cycle. The programming of the Configuration Register should

take place in a time of t

P, during which time the Status Register will indicate that the device is

busy. The device must be power-cycled after the completion of the program cycle to set the

“power of 2” page size. If the device is powered-down before the completion of the program

cycle, then setting the Configuration Register cannot be guaranteed. However, the user should

check bit 0 of the status register to see whether the page size was configured for binary page

size. If not, the command can be re-issued again.

Figure 13-1. Erase Sector Protection Register

14. Manufacturer and Device ID Read

Identification information can be read from the device to enable systems to electronically query

and identify the device while it is in system. The identification method and the command opcode

comply with the JEDEC standard for “Manufacturer and Device ID Read Methodology for SPI

Compatible Serial Interface Memory Devices”. The type of information that can be read from the

device includes the JEDEC defined Manufacturer ID, the vendor specific Device ID, and the ven-

dor specific Extended Device Information.

Command

Byte 1

Byte 2

Byte 3

Byte 4

Power of Two Page Size

3DH

2AH

80H

A6H

Opcode

Byte 1

Opcode

Byte 2

Opcode

Byte 3

Opcode

Byte 4

Each transition

represents 8 bits

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