 2010 Microchip Technology Inc.

DS22021F-page 19

25AA512

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 16 bits (A15-A0). After

the last bit of the dummy address is clock 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 ensure

FIGURE 2-13:

RELEASE FROM DEEP POWER-DOWN

SO

SI

SCK

CS

0

23456789 10 11

21 22 23 24 25 26 27 28 29 30 31

1

01

1

0

1

0

11

15 14 13 12

210

76543210

Instruction

16-bit Address

Electronic Signature Out

High-Impedance

0

101001

0

Manufacturer’s ID = 0x29

SO

SI

SCK

CS

0

234

567

1

01

1

0

1

0

11

Instruction

High-Impedance