25AA1024 View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

25AA1024

1 Mbit SPI Bus Serial EEPROM

Microchip Technology 

25AA1024/25LC1024

2.12 RELEASE FROM DEEP POWER-

DOWN AND READ ELECTRONIC

SIGNATURE

Once the device has entered Deep Power-Down

mode all instructions are ignored except the release

from Deep Power-down and Read Electronic Signa-

ture command. This command can also be used when

the device is not in Deep Power-down, to read the

electronic signature out on the SO pin unless another

command is being executed such as Erase, Program

or Write STATUS register.

Release from Deep Power-Down mode and Read

Electronic Signature is entered by driving CS low,

followed by the RDID instruction code (Figure 2-12)

and then a dummy address of 24 bits (A23-A0). After

the last bit of the dummy address is clocked in, the

8-bit Electronic signature is clocked out on the SO

pin.

After the signature has been read out at least once,

the sequence can be terminated by driving CS high.

The device will then return to Standby mode and will

wait to be selected so it can be given new instructions.

If additional clock cycles are sent after the electronic

signature has been read once, it will continue to output

the signature on the SO line until the sequence is

terminated.

FIGURE 2-12:

RELEASE FROM DEEP POWER-DOWN AND READ ELECTRONIC SIGNATURE

CS

SCK

SI

SO

0 1 2 3 4 5 6 7 8 9 10 11

29 30 31 32 33 34 35 36 37 38 39

Instruction

24-bit Address

1 0 1 0 1 0 1 1 23 22 21 20

210

High-Impedance

Electronic Signature Out

76543210

00101001

Manufacturers ID 0x29

Driving CS high after the 8-bit RDID command, but before the Electronic Signature has been transmitted, will still

ensure the device will be taken out of Deep Power-Down mode. However, there is a delay TREL that occurs before the

device returns to Standby mode (ICCS), as shown in Figure 2-13.

FIGURE 2-13:

RELEASE FROM DEEP POWER-DOWN AND READ ELECTRONIC SIGNATURE

CS

SCK

SI

01234567

Instruction

101 01 011

High-Impedance

SO

TREL

DS21836D-page 18

Preliminary

© 2007 Microchip Technology Inc.

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