M25P32 datasheet(25/39 Pages) STMICROELECTRONICS

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M25P32

Release from Deep Power-down and Read

Electronic Signature (RES)

Once the device has entered the Deep Power-

down mode, all instructions are ignored except the

Release from Deep Power-down and Read Elec-

tronic Signature (RES) instruction. Executing this

instruction takes the device out of the Deep Pow-

er-down mode.

The instruction can also be used to read, on Serial

Data Output (Q), the old-style 8-bit Electronic Sig-

nature, whose value for the M25P32 is 15h.

Please note that this is not the same as, or even a

subset of, the JEDEC 16-bit Electronic Signature

that is read by the Read Identifier (RDID) instruc-

tion. The old-style Electronic Signature is support-

ed for reasons of backward compatibility, only, and

should not be used for new designs. New designs

should, instead, make use of the JEDEC 16-bit

Electronic Signature, and the Read Identifier

(RDID) instruction.

Except while an Erase, Program or Write Status

Deep Power-down and Read Electronic Signature

(RES) instruction always provides access to the

old-style 8-bit Electronic Signature of the device,

and can be applied even if the Deep Power-down

mode has not been entered.

Any Release from Deep Power-down and Read

Electronic Signature (RES) instruction while an

Erase, Program or Write Status Register cycle is in

progress, is not decoded, and has no effect on the

cycle that is in progress.

The device is first selected by driving Chip Select

(S) Low. The instruction code is followed by 3

dummy bytes, each bit being latched-in on Serial

Data Input (D) during the rising edge of Serial

Clock (C). Then, the old-style 8-bit Electronic Sig-

nature, stored in the memory, is shifted out on Se-

rial Data Output (Q), each bit being shifted out

during the falling edge of Serial Clock (C).

The instruction sequence is shown in Figure 20..

The Release from Deep Power-down and Read

Electronic Signature (RES) instruction is terminat-

ed by driving Chip Select (S) High after the Elec-

tronic Signature has been read at least once.

Sending additional clock cycles on Serial Clock

(C), while Chip Select (S) is driven Low, cause the

Electronic Signature to be output repeatedly.

When Chip Select (S) is driven High, the device is

put in the Standby Power mode. If the device was

not previously in the Deep Power-down mode, the

transition to the Standby Power mode is immedi-

ate. If the device was previously in the Deep Pow-

er-down mode, though, the transition to the

Standby Power mode is delayed by tRES2, and

Chip Select (S) must remain High for at least

tRES2(max), as specified in Table 14.. Once in the

Standby Power mode, the device waits to be se-

lected, so that it can receive, decode and execute

instructions.

Figure 20. Release from Deep Power-down and Read Electronic Signature (RES) Instruction

Sequence and Data-Out Sequence

Note: The value of the 8-bit Electronic Signature, for the M25P32, is 15h.

AI04047C

3456789 10

28 29 30 31 32 33 34 35

22 21

3210

36 37 38

765432

High Impedance

Electronic Signature Out

Instruction

3 Dummy Bytes

MSB

Stand-by Mode

Deep Power-down Mode

MSB

tRES2

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