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NX25F011B

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

Unspecified 

NX25F011B

NX25F021B

NX25F041B

SERIAL FLASH SECTOR COMMANDS

Read From Sector (52H)

Reading from a sector is accomplished by first bringing

CS low then shifting in the Read from Sector command

(52H) followed by its 16-bit “sector-address” field.

Although the sector-address field is 16-bits, only bits

S[8:0] for the NX25F011B (0-1FFH), S[9:0] for the

NX25F021B (0-3FFH), S[10:0] for the NX25F041B

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

are not used but must be clocked using 0 for data. Next

a 16-bit “byte-address” field is clocked into the device to

designate the starting location within the 264-byte

sector. Only B[8:0] of the byte-address field are used;

the uppermost bits are not used but must be clocked in

(use 0 for data). Only byte-addresses of 0 to 107H

(264 bytes) are valid. Following the byte-address field,

16 control clocks are required with data=0.

The Serial Data Output (SO) will change from a

high-impedance state and begin to drive the output with

Ready/Busy status RB[15:0]. If SO uses the rising edge

of clock (configuration register RCE=1), the output will

be driven after the last control clock. If SO uses the

falling edge of clock (RCE=0), the output will be driven

on the next falling edge of clock. If the array is not busy,

the output status will be 9999H, followed by the sector

data on the SO pin. If the array is busy, the status will be

6666H, and the command should be terminated and

restarted after a ready state occurs. The data field is

shifted out with the least significant byte first (i.e.,

byte-00H, byte-01H, ...). The bit order within each byte

is the most significant bit first (i.e.,D7,...D0). The

byte-address is internally incremented to the next higher

byte address as the clock continues. When the highest

byte-address (107H) is reached, the address counter

rolls over to byte-0H and continues to increment. Assert-

ing the CS pin high completes (or terminates) the

command. Detailed timing for the Read from Sector

command is shown in Figure 10.

Read From Sector with Auto Increment (50H)

The Read from sector with Auto Increment command

operates similar to the standard Read from Sector com-

mand except that after the last bit of the current sector is

clocked the next sequentially addressed sector will be

automatically selected for reading without requiring the nine

byte command sequence to be issued. This allows the

entire device or a large number of sectors to be read out with

a single command.

Read From Sector Low Frequency (51H) and

Read From Sector Low Frequency with Auto

Increment (5BH)

The Read From Sector at Low Frequency command (51H)

and Read From Sector Low Frequency with Auto Increment

command (5BH) can reduce power consumption during read

operations by 25%-40% when the system clock frequency

is 1 MHz or lower. The command sequences are identical to

the standard commands.

Read from

Sector

Command

Sector

Address*

Byte

Address** 16 Clocks

SI 52H, 50H, 51H, 53H S[15:0]

B[15:0]

0000H

SO

RB[15:0]

First Byte - Last Byte

Read/Busy

Status

Read Sector Data

*The sector address only uses bits [8:0], [9:0] or [10:0] Depending on the density

**The byte address only uses bits [8:0]. Byte address must be 0000h for Auto Increment commands

16

NexFlash Technologies, Inc.

PRELIMINARY NXSF016F-1201

12/12/01 ©

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