High noise (~80mV) when measuring voltages using SAADC on nRF52840 (AIN0, AIN4, AIN5)

[Hassen]

Hi,
I'm using the nRF52840 to measure voltages through the SAADC. I'm observing a measurement noise of around 80mV peak-to-peak on inputs AIN0, AIN4, and AIN5.

Here are the details of my configuration:

• SAADC reference: internal Vref = 0.6V

• Gain: 1/6

• Input voltage: around 3.5V

• Mode: single-ended

• Supply:  battery 9,6V

• the nRF52840 is powered by a MAX20075DATCA DC/DC regulator, providing a stable 3.3V.

I would like to know:

• What are the recommended ways to reduce the noise on the SAADC measurements?

Thank you in advance for your help!

[Kenneth]

Hi,

I notice you are trying to measure a voltage that is higher than VDD, which is not possible, I suspect that may partially be part of the problem here.

Kenneth

[Hassen]

Hi 
I have a voltage divider at the analog input, so the voltage does not exceed 3V