NX25F011B 查看數據表（PDF） - Unspecified

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NX25F011B

1M-BIT, 2M-BIT, AND 4M-BIT SERIAL FLASH MEMORIES WITH 4-PIN SPI INTERFACE

Unspecified 

NX25F011B

NX25F021B

NX25F041B

Serial SRAM

One of the most powerful features of the NX25F011B,

NX25F021B, and NX25F041B is the integrated Serial

SRAM. The main purpose of the Serial SRAM is to serve

as the primary buffer for sector data to be written into the

Serial Flash memory array. Using the Write to Sector

command, data is first shifted into the SRAM from the SPI

bus. When the command sequence has been completed, the

entire 264-bytes is written to the selected sector. See

Erase/Write cycle timing (tWP).

The SRAM is fully byte-addressable. Thus, the entire

264-bytes, a single byte, or a sequence of bytes can be read

from, or written to the SRAM. This allows the SRAM to be

used as a temporary work area for read-modify-write

operations prior to a sector write.

The Transfer Sector to SRAM command allows the con-

tents of a specified sector of Flash memory to be moved to

the SRAM. This can be useful when only a portion of a sector

needs to be altered. In this case the sector is first transferred

to the SRAM, where modifications are made using the Write

to SRAM command. Once complete, a Transfer SRAM to

Sector command is used to update the sector.

The Compare Sector command allows the contents of the

SRAM to be compared with the specified sector in memory.

The result of the compare is set in the status register. This

command is useful for performing a fast verify of the last

sector write operation (see Write/ Verify Flow towards the

end of this data sheet). This command can be useful when

re-writing multi-sector files that have only minor changes

from the previous write. If the new data in the SRAM is the

same as the previously written data, the sector write can

be skipped. Used in this way, the command saves time

that would have been used for re-programming. It also

extends the endurance of the Flash memory cells.

READ FROM

DEVICE INFORMATION

SECTOR

READ FROM

SECTOR

SCK

CS

SI

SO

SPI

COMMAND

AND

CONTROL

LOGIC

CONFIGURATION

REGISTER

STATUS

REGISTER

COMPARE SECTOR

TO SRAM

DEVICE INFORMATION SECTOR

SERIAL FLASH MEMORY ARRAY

512, 1024 AND 2048 BYTE-ADDRESSABLE

SECTORS OF 264-BYTES EACH

TRANSFER

SECTOR TO

SRAM

READ FROM

OR WRITE TO

SRAM

WRITE TO SECTOR

(VIA SRAM)

SERIAL SRAM

Note:

1. A single byte, several bytes, or all bytes of a Flash sector, the SRAM, or Program Buffer may be addressed.

2. All double lines represent implied connections or actions.

Figure 5. Command Relationships of the SPI Interface, Serial Flash Memory Array and SRAM

8

NexFlash Technologies, Inc.

PRELIMINARY NXSF016F-1201

12/12/01 ©

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