oscillation at the embed analog front end circuits of SAADC in nRF52832

[Kiyoshi Iwai]

Hello,

I found the strange phenomena on nRF52832.

By using the SAADC, I have some noise on ADC Data only at a certain temperature range.

Temperature range is depend on individual IC.

I might be the circuit oscillation at analog front end of SAADC, I think.

(internal reference voltage or op amp etc,)

I tried to switch DCDC on/off, but there's no difference on phenomena.

Anyone can resolve it?

I attach the files of real data and measurement condition.

Best regards,

Kiyoshi Iwai

3426.SAADC_noise_devzone.zip

[Kenneth]

Hi Kiyoshi,

Thank you for all the measurements and your patience on this case.

I have talked to the designers, and we kindly ask you to do one more measurement. The designers believe the root cause may be noise from the internal reference voltage (0.6V). Can you kindly repeat the measurements using VDD as reference? 

I have made this case private now, so we can share confidential information if needed between us and Avnet.

Best regards,
Kenneth