Table 32. Peripheral Current Consumption - STMicroelectronics STM32F042F4 Manual

Electrical characteristics
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.
Any floating input pin can also settle to an intermediate voltage level or switch inadvertently,
Caution:
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 32: Peripheral current
to the current consumption. When an I/O pin switches, 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
V
DDIOx
f
SW
C is the total capacitance seen by the I/O pin: C = C
C is the PCB board capacitance including the pad pin.
S
The test pin is configured in push-pull output mode and is toggled by software at a fixed
frequency.
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consumption), the I/Os used by an application also contribute
is the current sunk by a switching I/O to charge/discharge the capacitive load
is the I/O supply voltage
is the I/O switching frequency
DocID025832 Rev 5
×
I V f
=
SW DDIOx SW
STM32F042x4 STM32F042x6
×
C
+ C + C
INT EXT S