NX25F080A-3TE-R データシートの表示（PDF） - NexFlash -> Winbond Electronics

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NX25F080A-3TE-R

8M-BIT SERIAL FLASH MEMORY WITH 4-PIN SPI INTERFACE

NexFlash -> Winbond Electronics 

NX25F080A

Serial SRAM and Program Buffer

One of the most powerful features of the NX25F080A is

the integrated Serial SRAM and its associated Program

Buffer. Together, the 536-byte Serial SRAM and 536-byte

Program Buffer provide up to 1072 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 sector data to be written into the Serial

Flash memory array. Using the Write to Sector com-

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

bus. When the command sequence has been completed,

the entire 536-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

536-bytes, a single byte, or a sequence of bytes can be

2 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.

3 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

4 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.

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

2048 BYTE-ADDRESSABLE

SECTORS OF 536-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 NXSF005C-0699

06/11/99 ©

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