Datasheet

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STM32F20xxx Functional overview
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3.34 ADCs (analog-to-digital converters)
Three 12-bit analog-to-digital converters are embedded and each ADC shares up to 16
external channels, performing conversions in the single-shot or scan mode. In scan mode,
automatic conversion is performed on a selected group of analog inputs.
Additional logic functions embedded in the ADC interface allow:
• Simultaneous sample and hold
• Interleaved sample and hold
The ADC can be served by the DMA controller. An analog watchdog feature allows very
precise monitoring of the converted voltage of one, some or all selected channels. An
interrupt is generated when the converted voltage is outside the programmed thresholds.
The events generated by the timers TIM1, TIM2, TIM3, TIM4, TIM5 and TIM8 can be
internally connected to the ADC start trigger and injection trigger, respectively, to allow the
application to synchronize A/D conversion and timers.
3.35 DAC (digital-to-analog converter)
The two 12-bit buffered DAC channels can be used to convert two digital signals into two
analog voltage signal outputs. The design structure is composed of integrated resistor
strings and an amplifier in inverting configuration.
This dual digital Interface supports the following features:
• two DAC converters: one for each output channel
• 8-bit or 12-bit monotonic output
• left or right data alignment in 12-bit mode
• synchronized update capability
• noise-wave generation
• triangular-wave generation
• dual DAC channel independent or simultaneous conversions
• DMA capability for each channel
• external triggers for conversion
• input voltage reference V
REF+
Eight DAC trigger inputs are used in the device. The DAC channels are triggered through
the timer update outputs that are also connected to different DMA streams.
3.36 Temperature sensor
The temperature sensor has to generate a voltage that varies linearly with temperature. The
conversion range is between 1.8 and 3.6 V. The temperature sensor is internally connected
to the ADC1_IN16 input channel which is used to convert the sensor output voltage into a
digital value.
As the offset of the temperature sensor varies from chip to chip due to process variation, the
internal temperature sensor is mainly suitable for applications that detect temperature
changes instead of absolute temperatures. If an accurate temperature reading is needed,
then an external temperature sensor part should be used.