NX25F011A 查看數據表（PDF） - NexFlash -> Winbond Electronics

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NX25F011A

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

NexFlash -> Winbond Electronics 

NX25F011A

NX25F041A

Serial SRAM and Program Buffer

One of the most powerful features of the NX25F011A and

NX25F041A is the integrated Serial SRAM and its associ-

ated Program Buffer. Together, the 264-byte Serial SRAM

and 264-byte Program Buffer provide up to 528-bytes of

usable SRAM storage. The SRAM can be used in

conjunction with the Flash memory or independently.

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

primary buffer for 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 transferred to the Program Buffer. The

Program Buffer supports the array during the

Erase/Write cycle (tWP), freeing the SRAM to accept

new data. This double-buffering scheme increases

erase/write transfer rates and can eliminate the need for

external RAM buffers (Figure 5).

1

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

2 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-

3 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

4 to SRAM command. Once complete, a Transfer SRAM to

Sector command is used to update the sector.

READ FROM

DEVICE INFORMATION

SECTOR

READ FROM

SECTOR

DEVICE INFORMATION SECTOR

SCK

CS

SI

SO

SPI

COMMAND

AND

CONTROL

LOGIC

CONFIGURATION

REGISTER

STATUS

REGISTER

COMPARE SECTOR

TO SRAM

READ FROM

PROGRAM BUFFER

READ FROM

OR WRITE TO

SRAM

WRITE TO SECTOR

(VIA SRAM &

PROGRAM BUFFER)

SERIAL FLASH MEMORY ARRAY

512 AND 2048 BYTE-ADDRESSABLE

SECTORS OF 264-BYTES EACH

TRANSFER

SECTOR TO

SRAM

TRANSFER SRAM TO SECTOR

(VIA PROGRAM BUFFER)

TRANSFER SRAM TO

PROGRAM BUFFER

PROGRAM BUFFER

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.

TRANSFER PROGRAM

BUFFER TO SRAM

5

6

7

8

9

10

11

12

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

NexFlash Technologies, Inc.

5

PRELIMINARY NXSF014B-0699

06/11/99

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