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

[Kiyoshi Iwai]

Hello Kenneth,

I checked this again by using VDD/4 as reference, but this issue still occurred.

Do you have next counter measure?

And why does not your designer check the analog circuits (amp, LDO, etc.,)?

I think the root cause of this issue is not software but hardware.

So I strongly recommend to check the internal circuits operation by hardware designer himself.

By the way, Avnet says they can not see this communication because of private mode.

Could you disclose this to Avnet too?

 

Best regards,

kiyoshi Iwai