25AA1024/25LC1024

DS21836D-page 18

Preliminary

© 2007 Microchip Technology Inc.

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

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

FIGURE 2-13:

RELEASE FROM DEEP POWER-DOWN AND READ ELECTRONIC SIGNATURE

SO

SI

SCK

CS

0

23456789 10 11

29 30 31 32 33 34 35 36 37 38 39

1

01

1

0

1

0

11

23 22 21 20

210

76543210

Instruction

24-bit Address

Electronic Signature Out

High-Impedance

0

101001

0

Manufacturers ID 0x29

SO

SI

SCK

CS

0

234

567

1

01

1

0

1

0

11

Instruction

High-Impedance