AT25DF641_13 datasheet(41/56 Pages) ETC2

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AT25DF641

3680F–DFLASH–4/10

11.2. Read Manufacturer and Device ID

Identification information can be read from the device to enable systems to electronically query and identify the

device while it is in system. The identification method and the command opcode comply with the JEDEC standard

for “Manufacturer and Device ID Read Methodology for SPI Compatible Serial Interface Memory Devices”. The

type of information that can be read from the device includes the JEDEC defined Manufacturer ID, the vendor

specific Device ID, and the vendor specific Extended Device Information.

The Read Manufacturer and Device ID command is limited to a maximum clock frequency of fCLK. Since not all

Flash devices are capable of operating at very high clock frequencies, applications should be designed to read

the identification information from the devices at a reasonably low clock frequency to ensure that all devices to be

used in the application can be identified properly. Once the identification process is complete, the application can

then increase the clock frequency to accommodate specific Flash devices that are capable of operating at the

higher clock frequencies.

To read the identification information, the

pin must first be asserted and the opcode of 9Fh must be clocked

into the device. After the opcode has been clocked in, the device will begin outputting the identification data on

the SO pin during the subsequent clock cycles. The first byte that will be output will be the Manufacturer ID

followed by two bytes of Device ID information. The fourth byte output will be the Extended Device Information

String Length, which will be 00h indicating that no Extended Device Information follows. After the Extended

Device Information String Length byte is output, the SO pin will go into a high-impedance state; therefore,

additional clock cycles will have no affect on the SO pin and no data will be output. As indicated in the JEDEC

standard, reading the Extended Device Information String Length and any subsequent data is optional.

Deasserting the

pin will terminate the Manufacturer and Device ID read operation and put the SO pin into a

high-impedance state. The

pin can be deasserted at any time and does not require that a full byte of data be

read.

Table 11-1.

Manufacturer and Device ID Information

Byte No.

Data Type

Value

Manufacturer ID

1Fh

Device ID (Part 1)

48h

Device ID (Part 2)

00h

Extended Device Information String Length

00h

Table 11-2.

Manufacturer and Device ID Details

Data Type

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Hex

Value Details

Manufacturer ID

JEDEC Assigned Code

1Fh JEDEC Code:

0001 1111 (1Fh for Adesto)

Device ID (Part 1)

Family Code

Density Code

48h Family Code:

010 (AT25DF/26DFxxx series)

Density Code:

01000 (64-Mbit)

Device ID (Part 2)

Sub Code

Product Version Code

00h Sub Code:

000 (Standard series)

Product Version: 00000 (Initial version)

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