Datasheet

25LC1024
DS22064D-page 18  2010 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
ensure the device will be taken out of Deep Power-Down mode. However, there is a delay T
REL
that occurs before the
device returns to Standby mode (I
CCS
), as shown in Figure 2-13.
FIGURE 2-13: RELEASE FROM DEEP POWER-DOWN AND READ ELECTRONIC SIGNATURE
SO
SI
SCK
CS
0 234567891011 29303132333435363738391
0110101123 22 21 20
210
76543210
Instruction 24-bit Address
Electronic Signature Out
High-Impedance
0 1010010
Manufacturers ID 0x29
SO
SI
SCK
CS
0 2345671
01101011
Instruction
High-Impedance
T
REL