Datasheet

M95128-W M95128-R M95128-DF Operating features
Doc ID 5798 Rev 16 13/49
5 Operating features
5.1 Supply voltage (V
CC
)
5.1.1 Operating supply voltage V
CC
Prior to selecting the memory and issuing instructions to it, a valid and stable V
CC
voltage
within the specified [V
CC
(min), V
CC
(max)] range must be applied (see Operating conditions
in Section 9: DC and AC parameters). This voltage must remain stable and valid until the
end of the transmission of the instruction and, for a Write instruction, until the completion of
the internal write cycle (t
W
). In order to secure a stable DC supply voltage, it is
recommended to decouple the V
CC
line with a suitable capacitor (usually of the order of
10 nF to 100 nF) close to the V
CC
/V
SS
device pins.
5.1.2 Device reset
In order to prevent erroneous instruction decoding and inadvertent Write operations during
power-up, a power-on-reset (POR) circuit is included. At power-up, the device does not
respond to any instruction until VCC reaches the POR threshold voltage. This threshold is
lower than the minimum V
CC
operating voltage (see Operating conditions in Section 9: DC
and AC parameters).
At power-up, when V
CC
passes over the POR threshold, the device is reset and is in the
following state:
● in Standby Power mode,
● deselected,
● Status Register values:
– The Write Enable Latch (WEL) bit is reset to 0.
– The Write In Progress (WIP) bit is reset to 0.
– The SRWD, BP1 and BP0 bits remain unchanged (non-volatile bits).
It is important to note that the device must not be accessed until V
CC
reaches a valid and
stable level within the specified [V
CC
(min), V
CC
(max)] range, as defined under Operating
conditions in Section 9: DC and AC parameters.
5.1.3 Power-up conditions
When the power supply is turned on, V
CC
rises continuously from V
SS
to V
CC
. During this
time, the Chip Select (S
) line is not allowed to float but should follow the V
CC
voltage. It is
therefore recommended to connect the S
line to V
CC
via a suitable pull-up resistor (see
Figure 5).
In addition, the Chip Select (S
) input offers a built-in safety feature, as the S input is edge-
sensitive as well as level-sensitive: after power-up, the device does not become selected
until a falling edge has first been detected on Chip Select (S
). This ensures that Chip Select
(S
) must have been high, prior to going low to start the first operation.
The V
CC
voltage has to rise continuously from 0 V up to the minimum V
CC
operating voltage
defined under Operating conditions in Section 9: DC and AC parameters, and the rise time
must not vary faster than 1 V/µs.