The STM32G071RB generates spikes on the ADC channel 11.

[AljazKr]

Hi,

I have a design where ADC channel 11 is used for sampling BLDC motor current via shunt resistor.

If motor is stopped it can be observed a spikes with aplitude 200 mV directly on the MCU pin PB10 to which the ADC channel 11 is connected.

The spikes has the same frequency as the ADC trigger and they are also directly in phase with the ADC trigger signal.

MCU input pin is configured as analog input with no-pull-up. If ADC channel is disabled, the spikes dissaper.

ADC is triggered by TIM3 with frequency of 1 kHz.

Thank you in advance for every suggestion!

[waclawek.jan]

This is normal. ADC connects a sampling capacitor at the beginning of the sampling, and it charges/discharges from the signal.

Use higher impedance signal or longer sampling time to allow the signal to settle.

JW