Datasheet

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STM32F051x4 STM32F051x6 STM32F051x8 Electrical characteristics
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trigger circuits used to discriminate the input value. Unless this specific configuration is
required by the application, this supply current consumption can be avoided by configuring
these I/Os in analog mode. This is notably the case of ADC input pins which should be
configured as analog inputs.
Caution: Any floating input pin can also settle to an intermediate voltage level or switch inadvertently,
as a result of external electromagnetic noise. To avoid current consumption related to
floating pins, they must either be configured in analog mode, or forced internally to a definite
digital value. This can be done either by using pull-up/down resistors or by configuring the
pins in output mode.
I/O dynamic current consumption
In addition to the internal peripheral current consumption measured previously (see
Table 31: Peripheral current consumption), the I/Os used by an application also contribute
to the current consumption. When an I/O pin switch
es, it uses the current from the I/O
supply voltage to supply the I/O pin circuitry and to charge/discharge the capacitive load
(internal or external) connected to the pin:
where
I
SW
is the current sunk by a switching I/O to charge/discharge the capacitive load
V
DDIOx
is the I/O supply voltage
f
SW
is the I/O switching frequency
C is the total capacitance seen by the I/O pin: C = C
INT
+ C
EXT
+ C
S
C
S
is the PCB board capacitance including the pad pin.
The test pin is configured in push-pull output
mode and is toggled by software at a fixed
frequency.
I
SW
V
DDIOx
f
SW
C××=
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