NX25F011B View Datasheet(PDF) - NexFlash -> Winbond Electronics

Part Name

Description

Manufacturer

NX25F011B

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

NexFlash -> Winbond Electronics 

NX25F011B

NX25F021B

NX25F041B

Using the SRAM Independent of Flash Memory

The SRAM can be used independently of Flash memory

operations for lookup tables, variable storage, or scratch

pad purposes. If the Flash memory needs to be written to

while SRAM is being used for a different purpose, the

contents can be temporarily stored to a sector and then

transferred back again when needed. The SRAM can be

especially useful for RAM-limited microcontroller-based

systems, eliminating the need for external SRAM and

freeing pins for other purposes. It can also make it possible

to use small pin-count microcontrollers, since only a few

pins are needed for the interface instead of the 20-40 pins

required for parallel bus-oriented Flash devices.

Write Protection

The NX25F011B, NX25F021B, and NX25F041B provide ad-

vanced software and hardware write protection

features. Software-controlled write protection of the entire

array is handled using the Write Enable and Write Disable

commands. Hardware write protection is possible using the

Write Protect pin (WP). Write-protecting a portion of Flash

memory is accommodated by programming a write protect

range in the configuration register. For applications

needing a portion of the memory to be permanently

write-protected or a fixed configuration register value, a

onetime programmable write protection feature is supported.

Contact NexFlash for further information.

Configuration Register

The Configuration Register stores the current configuration

of the HOLD-R/B pin, read clock edge and write protect

range (Figure 7). The configuration register is accessed

using the Write and Read Configuration Register

commands. The non-volatile configuration register will

maintain its setting even when power is removed.

To avoid unnecessary programming of the configuration

register, and to save time during power-up, the configuration

register should be read upon power-up and compared to the

intended setting before sending a Write Configuration

Register command (Figure 6).

1

System Power-up

Read Device Information Sector,

2

Verify Device Density and Type

3

Read Configuration Register

Verify bits are Set as Needed

4

Configuration

Yes

Setting is Correct?

5

No

Write Configuration Register

to Correct Setting

6

7

Application Routines

8

9 Figure 6. Flow Chart for Checking the Configuration

Register upon Power-up

10

11

12

NexFlash Technologies, Inc.

9

PRELIMINARY NXSF016F-1201

12/12/01 ©

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