45PE80 Ver la hoja de datos (PDF) - Micron Technology

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45PE80

Micron Serial NOR Flash Memory

Micron Technology 

75MHz, Serial Peripheral Interface Flash Memory

Operating Features Overview

Operating Features Overview

Sharing the Overhead of Modifying Data

To write or program 1 or more data bytes, two commands are required: WRITE ENABLE

which is 1 byte, and a PAGE WRITE or PAGE PROGRAM command sequence, which

consists of 4 bytes plus data. This is followed by the internal cycle of duration tPW or tPP.

To share this overhead, the PAGE WRITE or PAGE PROGRAM command allows up to 256

bytes to be programmed (changing bits from 1 to 0) or written (changing bits to 0 or 1)

at a time, provided that they lie in consecutive addresses on the same page of memory.

Easy Method to Modify Data

The PAGE WRITE command provides a convenient way of modifying data (up to 256

contiguous bytes at a time) and requires the start address and the new data in the in-

struction sequence.

The PAGE WRITE command is entered by driving chip select (S#) LOW, and then trans-

mitting the instruction byte, 3 address bytes A[23:0] and at least 1 data byte, and then

driving S# HIGH. While S# is being held LOW, the data bytes are written to the data buf-

fer, starting at the address given in the third address byte A[7:0]. When S# is driven

HIGH, the WRITE cycle starts. The remaining unchanged bytes of the data buffer are

automatically loaded with the values of the corresponding bytes of the addressed mem-

ory page. The addressed memory page is then automatically put into an ERASE cycle.

Finally, the addressed memory page is programmed with the contents of the data buf-

fer.

All of this buffer management is handled internally, and is transparent to the user. The

user may alter the contents of the memory on a byte-by-byte basis. For optimized tim-

ings, it is recommended to use the PAGE WRITE command to write all consecutive tar-

geted bytes in a single sequence versus using several PAGE WRITE sequences with each

containing only a few bytes.

Fast Method to Modify Data

The PAGE PROGRAM command provides a fast way of modifying data (up to 256 con-

tiguous bytes at a time), provided that it only involves resetting bits to 0 that had previ-

ously been set to 1.

This might be:

• When the designer is programming the device for the first time.

• When the designer knows that the page has already been erased by an earlier PAGE

ERASE or SECTOR ERASE command. This is useful, for example, when storing a fast

stream of data, having first performed the erase cycle when time was available.

• When the designer knows that the only changes involve resetting bits to 0 that are still

set to 1. When this method is possible, it has the additional advantage of minimizing

the number of unnecessary ERASE operations and the extra stress incurred by each

page.

For optimized timings, it is recommended to use the PAGE PROGRAM command to

program all consecutive targeted bytes in a single sequence versus using several PAGE

PROGRAM sequences with each containing only a few bytes.

PDF: 09005aef845660e5

m45pe80.pdf - Rev. C 03/14 EN

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© 2011 Micron Technology, Inc. All rights reserved.

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