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AT45DB021E

DS-AT45DB021E—8789J—03/2021

Manufacturer and Device ID Read

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

device while it is in the 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, design applications to read the identification

information from the devices at a reasonably low clock frequency; this ensures 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 CS pin must first be asserted, and then the opcode 9Fh must be clocked

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

SO pin during the subsequent clock cycles. The first byte to be output is the Manufacturer ID, followed by two bytes

of the Device ID information. The fourth byte output is the Extended Device Information (EDI) String Length, which

is 01h, indicating that one byte of EDI data follows. After the one byte of EDI data is output, the SO pin goes into a

high-impedance state; therefore, additional clock cycles have no affect on the SO pin and no data are output. As

indicated in the JEDEC Standard, reading the EDI String Length and any subsequent data is optional.

Deasserting the CS pin terminates the Manufacturer and Device ID Read operation and puts the SO pin into a

high-impedance state. The CS pin can be deasserted at any time and does not require that a full byte of data be

read.

Table 13-1. Manufacturer and Device ID Information

Byte No.

Data Type

Value

Manufacturer ID

1Fh

Device ID (Byte 1)

23h

Device ID (Byte 2)

00h

Extended Device Information (EDI) String Length

01h

[Optional to Read] EDI Byte 1

00h

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