STM32F401CD datasheet(72/135 Pages) STMICROELECTRONICS

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Electrical characteristics

STM32F401xD STM32F401xE

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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 (see Table 33: Peripheral current

consumption), the I/Os used by an application also contribute to the current consumption.

When an I/O pin switches, it uses the current from the MCU supply voltage to supply the I/O

pin circuitry and to charge/discharge the capacitive load (internal or external) connected to

the pin:

where

ISW is the current sunk by a switching I/O to charge/discharge the capacitive load

VDD is the MCU supply voltage

fSW is the I/O switching frequency

C is the total capacitance seen by the I/O pin: C = CINT+ CEXT

The test pin is configured in push-pull output mode and is toggled by software at a fixed

frequency.

ISW

VDD fSW C

STM32F401CD 数据表(PDF) 72 Page - STMicroelectronics