NX25F641C データシートの表示（PDF） - NexFlash -> Winbond Electronics

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NX25F641C

64M-BIT SERIAL FLASH MEMORY WITH 4-PIN SPI INTERFACE

NexFlash -> Winbond Electronics 

NX25F641C

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

transferred to the specified sector in memory array. See

tWP timing specifications. During this time the array and

SRAM will be “busy” and will ignore further array-related

commands until complete. All Ready/Busy status indica-

tors will indicate a busy status.

Write to SRAM Command (72H and 74H)

The Write to SRAM command (72H and 74H) provides

access to the 528-byte SRAM independently of any Flash

memory array operation. When CS is asserted high to

complete the command, the contents of the SRAM will be

maintained until overwritten through another command or

the power is removed. Using the Write to SRAM command,

data can be loaded in preparation of writing to a sector in

memory and then transferred to a selected sector using

the Transfer SRAM to Sector command. The TR bit in the

status register should be checked first if Transfer Sector to

SRAM or Compare Sector to SRAM commands are used.

TRANSFER AND REFRESH COMMANDS

Transfer SRAM to Sector (F3H and 94H)

The Transfer SRAM to Sector command (F6H and 98H)

will write the existing contents of the SRAM to the speci-

fied sector in memory. The command sequence is iden-

tical to that of the Write to Sector Using SRAM

command except that immediately after the sector

address field S[15:0] and 16 control clocks, the CS pin

is asser ted high. This automatically transfers the

528-bytes of SRAM data to the specified sector in the

memory array. During this time, the array and the SRAM

will be busy.

Compare Sector to SRAM (8DH and 8EH)

The Compare Sector to SRAM command (8DH/8EH) does

a bit-by-bit comparison of the data stored in the addressed

sector against data in the SRAM. The TR status bit will be

1 during the transfer compare operation. If any of the

compared bits are not equal, then the Compare Not Equal

(CNE) bit in the Status Register is set to a 1.

Refresh Sector Using SRAM (58H and 59H)

The Refresh Sector Using SRAM command (58H and

59H) will automatically transfer the contents of the

specified sector into the SRAM and then re-write the

data to the same sector. The purpose of this command

is to enhance data integrity and cycle endurance. Con-

tact NexFlash Marketing for updated information regard-

ing usage of the Refresh Command. During this com-

mand the array and the SRAM will be busy.

CONFIGURATION AND STATUS

COMMANDS

Read Device Information Sector (15H)

The Read Device Information command provides access

to a read-only sector that can be used to electronically

identify the NexFlash Serial Flash device being interfaced

to. Information available includes: part number, density,

voltage, temperature range, package type, and any

special options. Contact NexFlash for more detailed infor-

mation on the Device Information Sector format.

Read Configuration Register (8CH)

The Read Configuration Register command provides

access to the configuration register, which stores the

current configuration of the HOLD-R/B pin, read clock

edge, write protect range (see figure 5). A 16-bit Configu-

ration Data field CF[15:0] provides the contents of the

Configuration Register. Although the field is 16-bits long,

only bits CF[7:0] are used. All other upper bits are reserved

for future features.

Write Configuration Register (8AH)

The Write Configuration Register command provides

access to the configuration register which stores the cur-

rent configuration of the HOLD-R/B pin, read-data clock

edge and write protect range. The configuration register

is non-volatile. Once set using the Write Configuration

Register command, the contents will maintain even when

power is removed. Because the register’s state is stored

in non-volatile memory, there is a finite endurance limit to

the number of times it can be written to. To limit the

number of writes, it is recommended that before writing to

NexFlash Technologies, Inc.

17

PRELIMINARY NXSF032A-0502

05/06/02 ©

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