NX25F011A View Datasheet(PDF) - NexFlash -> Winbond Electronics

Part Name

Description

Manufacturer

NX25F011A

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

NexFlash -> Winbond Electronics 

NX25F011A

NX25F041A

Write to Sector

Before writing to a sector in the Flash memory array, all

hardware and software write protection must be in an

enabled state. This means that the WP pin must be in a

high state, a Write Enable command must have previ-

ously been issued, and the sector location that is to be

written to must be outside the write protect range set in

the configuration register. Additionally, the Ready/Busy

status should be checked to confirm that the memory

array is available to be written to.

The bit order within each byte is most significant bit first

1 (i.e., D7,...D0). The byte-address is automatically incre-

mented to the next higher byte address as the clock

continues. When the last byte address to be written is

reached, the command can be completed with an

additional eight control clocks (with data=0) followed by

2 asserting CS high. If the clock continues to increment

past the highest byte-address (107H), the address

counter will roll over to byte 0H.

Writing to a sector is accomplished by first bringing CS

low and shifting in the Write to Sector command (F3H)

followed by a 16-bit “sector-address” field. Although the

sector-address field is 16-bits, only bits S[8:0] for the

NX25F011A (0-1FFH) and S[10:0] for the NX25F041A

(0-7FFH) are used. The uppermost sector address bits

are not used but must be clocked in (use 0 data).

Following the sector address, a 16-bit “byte-address”

field is clocked into the device to designate the starting

location within the 264-byte sector. Only bits B[8:0] of the

byte-address field are used and only values of 0-107H

(264 bytes)are valid.

After the byte-address has been loaded, data is shifted

into the 264-byte SRAM, which serves as a temporary

storage buffer. Existing data in the SRAM will be written

over. The byte order of the data shifted into the SRAM

is least significant byte first (i.e., byte-00H, byte-01H,...).

3 After the CS pin is brought high, the data in the SRAM is

automatically transferred to the Program Buffer, which

handles the self-timed programming of the specified

sector in memory array. See tWP timing specifications.

4 During this time the array will be “busy” and will ignore

further array-related commands until complete. All

Ready/Busy status indicators will indicate a busy status.

Since the Program Buffer handles all array program-

ming, the SRAM is still available to be read from or

5 written to during the busy state. This allows the SRAM to

be written to in preparation of the next sector write. Once

the SRAM is loaded, its contents can be transferred to a

selected sector using the Transfer SRAM to Sector

6 command. Note that if the write operation is to be verified

the contents of the SRAM should be maintained. Detailed

clock timing for the Write to Sector command is shown

in Figure 11.

Write to

Sector

Command

Sector

Address*

Byte

Address**

Write Sector Data

Program

7

8 Clocks

Time

SI

F3H

SO

S[15:0]

B[15:0]

First Byte - Last Byte

00H

(tWP)

8

*The sector address only uses bits [8:0] or [10:0]

**The byte address only uses bits [8:0]

9

Transfer SRAM to Sector

The Transfer SRAM to Sector command (F3H) will write

the existing contents of the SRAM to the specified

sector in memory. The command sequence is identical

to that of the Write to Sector command except that

immediately after the sector address field S[15:0] and

16 control clocks, the CS pin is asserted high. This

automatically transfers the 264-bytes of SRAM data to the

Program Buffer, which handles the programming of the

specified sector in the memory array. During this time, the

array will be busy. Since the entire 264-bytes are trans-

ferred, the byte-address field B[15:0] is not used.

Transfer SRAM

to Sector

Sector

Command Address*

SI

F3H

S[15:0]

16 Clocks

0000H

10

Program Time

(tWP)

11

SO

*The sector address only uses bits [8:0] or [10:0]

12

NexFlash Technologies, Inc.

13

PRELIMINARY NXSF014B-0699

06/11/99

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