AT25SF641B datasheet(22/59 Pages) DIALOG

22 / 59 page

AT25SF641B

DS-AT25SF641B–191D–12-2020

Program and Erase Commands

8.1

Byte/Page Program (02h)

The Byte/Page Program command allows one to 256 bytes of data to be programmed into previously erased

memory locations. An erased memory location is one that has all eight bits set to the logical “1” state (a byte value

of FFh). Before a Byte/Page Program command can be started, the Write Enable command must have been

issued to the device (see “Write Enable (06h)”, on page 27) to set the Write Enable Latch (WEL) bit of the Status

To perform a Byte/Page Program command, an opcode of 02h must be clocked into the device, followed by the

three address bytes denoting the first byte location of the memory array to begin programming at. After the address

bytes have been clocked in, data can then be clocked into the device and is stored in an internal buffer.

If the starting memory address denoted by A23-A0 does not fall on an even 256-byte page boundary (A7-A0 are

not all 0), special circumstances regarding which memory locations to be programmed apply. In this situation, any

data that is sent to the device that goes beyond the end of the page wraps around back to the beginning of the

same page. For example, if the starting address denoted by A23-A0 is 0000FEh, and three bytes of data are sent

to the device, then the first two bytes of data are programmed at addresses 0000FEh and 0000FFh, and the last

byte of data is programmed at address 000000h. The remaining bytes in the page (addresses 000001h through

0000FDh) are not programmed and remain in the erased state (FFh). Furthermore, if more than 256 bytes of data

are sent to the device, only the last 256 bytes sent are latched into the internal buffer.

When the CS pin is deasserted, the device takes the data stored in the internal buffer and programs it into the

appropriate memory array locations based on the starting address specified by A23-A0 and the number of data

bytes sent to the device. If fewer than 256 bytes of data were sent to the device, the remaining bytes within the

page are not programmed and remain in the erased state (FFh). The programming of the data bytes is internally

self-timed and, if only programming a single byte, must take place in a time of tPP or tBP.

The three address bytes and at least one complete data byte must be clocked into the device before the CS pin is

deasserted, and the CS pin must be deasserted on even byte boundaries (multiples of eight bits); otherwise, the

device aborts the operation and no data is programmed into the memory array. Also, if the memory is in the

protected state, the Byte/Page Program command is not executed, and the device returns to the idle state once the

CS pin has been deasserted. The WEL bit in the Status Register is reset to the logical “0” state if: the program

cycle aborts due to an incomplete address being sent, an incomplete byte of data is sent, the CS pin is deasserted

on uneven byte boundaries, or the memory location to be programmed is protected.

While the device is programming, the Status Register can be read and indicates that the device is busy. For faster

throughput, it is recommended that the Status Register be polled, rather than waiting the tBP or tPP time to

determine if the data bytes have finished programming. At some point before the program cycle completes, the

WEL bit in the Status Register is reset to the logical “0” state.

Figure 8-1. Byte Program

SCK

MSB

00000010

410 11

812

37 38

31 32

29 30

OPCODE

HIGH-IMPEDANCE

AAAA

AAA

MSB

DDDDDDDD

ADDRESS BITS A23-A0

DATA IN

AT25SF641B Datenblatt(PDF) 22 Page - Dialog Semiconductor

AT25SF641B Datenblatt(HTML) 22 Page - Dialog Semiconductor

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59

Datenblatt Download

Link URL