
M25PX32
Power-up and Power-down
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Power-up and Power-down
At Power-up and Power-down, the device must not be selected (that is Chip Select (S) must
follow the voltage applied on V
CC
) until V
CC
reaches the correct value:
V
CC
(min) at Power-up, and then for a further delay of t
VSL
V
SS
at Power-down
A safe configuration is provided in
Section 3: SPI modes
.
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To avoid data corruption and inadvertent write operations during Power-up, a Power On
Reset (POR) circuit is included. The logic inside the device is held reset while V
CC
is less
than the Power On Reset (POR) threshold voltage, V
WI
– all operations are disabled, and
the device does not respond to any instruction.
Moreover, the device ignores all Write Enable (WREN), Page Program (PP), Dual Input Fast
Program (DIFP), Program OTP (POTP), Subsector Erase (SSE), Sector Erase (SE), Bulk
Erase (BE), Write Status Register (WRSR) and Write to Lock Register (WRLR) instructions
until a time delay of t
PUW
has elapsed after the moment that V
CC
rises above the V
WI
threshold. However, the correct operation of the device is not guaranteed if, by this time, V
CC
is still below V
CC
(min). No Write Status Register, Program or Erase instructions should be
sent until the later of:
t
PUW
after V
CC
has passed the V
WI
threshold
t
VSL
after V
CC
has passed the V
CC
(min) level
These values are specified in
Table 11
.
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If the time, t
VSL
, has elapsed, after V
CC
rises above V
CC
(min), the device can be selected for
READ instructions even if the t
PUW
delay has not yet fully elapsed.
After Power-up, the device is in the following state:
The device is in the Standby Power mode (not the Deep Power-down mode).
The Write Enable Latch (WEL) bit is reset.
The Write In Progress (WIP) bit is reset.
The Lock Registers are configured as: (Write Lock bit, Lock Down bit) = (0,0)
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Normal precautions must be taken for supply line decoupling, to stabilize the V
CC
supply.
Each device in a system should have the V
CC
line decoupled by a suitable capacitor close to
the package pins (generally, this capacitor is of the order of 100 nF).
At Power-down, when V
CC
drops from the operating voltage, to below the Power On Reset
(POR) threshold voltage, V
WI
, all operations are disabled and the device does not respond
to any instruction. (The designer needs to be aware that if Power-down occurs while a Write,
Program or Erase cycle is in progress, some data corruption may result.)
V
PPH
must be applied only when V
CC
is stable and in the V
CC
min to V
CC
max voltage
range.
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