NUCLEO-H723ZG BOARD ADC NOISE

[josegalicia]

Hi, I am planning on using STM32H723ZGT6 chip on one of my boards. I got the NUCLEO-H723ZG to measure the 12-bit ADC noise. From the datasheet for STM32H723ZGT6, the max ADC noise should be 5 times the LSB or 4.02mV. (1 LSB = 3.3/4096) 

I am getting 22.5641mV of noise. Which is more than 5 times the max ADC noise from the datasheet. Below is an image of the data. I didn't use any averaging. I used a 1.5V battery as my ADC input. 

I am wondering if this is expected ? I want to have 2 or 3 bits of noise on my board. Based on this, it seems I would be getting 5 bits of noise? Thank you!

[Andrew Neil]

The Nucleo boards aren't optimised for analogue ...

[ahsrabrifat]

The STM32 Nucleo board's power supply may be noisy due to USB or switching noise from the onboard LDO/Switching Regulator. Add capacitors (10uF + 100nF) near VREF+ and ADC inputs.