STM32 ADC Sampling Time Guide

Understand STM32 ADC sampling time, source impedance, settling error and how to choose safe ADC settings.

Why ADC sampling time matters

The ADC input capacitor must charge through the source impedance. If sampling time is too short, readings become inaccurate.

Higher source resistance requires longer sampling time. Voltage dividers, sensors and filters can all increase source impedance.

Use lower source impedance, add a buffer op-amp, increase sampling cycles or add a suitable capacitor near the ADC input.

Choose the next higher sampling time in CubeMX or firmware after calculating the minimum required time.

Try real values with the related STM32 calculator.

Use it for estimates and planning. Verify final hardware with the exact datasheet, reference manual and real measurements.

Current depends on STM32 family, voltage, clock speed, peripherals, firmware and board-level components.