M25P05-A Instructions
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6.12 Release from deep power-down and read electronic
signature (RES)
To take the device out of deep power-down mode, the release from deep power-down and
read electronic signature (RES) instruction must be issued. No other instruction must be
issued while the device is in deep power-down mode.
The instruction can also be used to read, on Serial Data output (Q), the 8-bit electronic
signature, whose value for the M25P05-A is 05h.
Except while an erase , program or write status registe r cycle is in progress , the release from
deep power-down and read electronic signature (RES) instruction always provides access
to the 8-bit electronic signature of the d evice, and can be applied even if the deep power-
down mode has not been entered.
Any rel ease from deep pow er-down and re ad electronic signature (RES) instruction wh ile 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 8-bit electronic sig nature, stored in the memory, is shifted out
on Serial Data output (Q), each bit being shifted out during the falling edge of Serial Clock
(C).
The instruction sequence is shown in Figure 18.
The release from de ep power-down and read electronic signature (RES) instruction is
terminated by driving Chip Select (S) High after the electronic signature has been read at
least once. Sending additional clock cycles on Serial Clock (C), while Chip Se lect (S) is
driven Low, cause the electronic signature to be output repe atedly.
When Chip Select (S) is driven High, the device is put in the standby power mode. If the
de vice was not pre viously in the deep power- down mode, the transition to the st andby po wer
mode is immediate . If the device was previously in the deep pow er-d o wn mode , th ough, th e
transitio n to the standby power mode is de layed by t RES2, and Chip Select (S) must remain
High f or at least tRES2(max), as specified in Table 15. Once in the st an dby power mod e, the
device waits to be selected, so that it can receive, decode and execute instructions.
Driving Chip Select (S) High after the 8-bit instruction b yte has be en receiv ed b y the device,
but before the whole of the 8-bit el ectronic signature has been transmitted for the first time
(as shown in Figure 19), still ensures that the device is put into standby power mode. If the
de vice was not pre viously in the deep power- down mode, the transition to the st andby po wer
mode is immediate . If the device was previously in the deep pow er-d o wn mode , th ough, th e
transitio n to the standby power mode is de layed by t RES1, and Chip Select (S) must remain
High f or at least tRES1(max), as specified in Table 15. Once in the st an dby power mod e, the
device waits to be selected, so that it can receive, decode and execute instructions.