nRF52832 32HMz HF clock noise / EMI issues

RE: nRF52832 32HMz HF clock noise / EMI issues

run_ar — Wed, 25 May 2016 11:38:36 GMT

Thank you for the update. I see that you are in touch with our HW guys, so I assume they are able to help you with this issue.

RE: nRF52832 32HMz HF clock noise / EMI issues

Visti Andresen — Thu, 19 May 2016 13:11:58 GMT

Yes it seems that I have completely overlooked the series resistance.

I'm planning to replace the Murata crystal with a Epson X1E0000210167

dk.farnell.com/.../2471847RL

Which has an ESR max of 40 Ohm, but does have a higher CL of 9pF

RE: nRF52832 32HMz HF clock noise / EMI issues

run_ar — Thu, 19 May 2016 12:58:21 GMT

ok, good. I took a brief look at the crystal you are using and it looks like the ESR is a bit High compared to what is stated in the nRF52832 product specification.
RS_HFXO_7PF Equivalent series resistance C0 = 7 pF 60 ohm(Max)
RS_HFXO_5PF Equivalent series resistance C0 = 5 pF 80 ohm(Max)
While the Murate crystal that you are using is C0 = 6 pF and 100 ohm Max.

RE: nRF52832 32HMz HF clock noise / EMI issues

Visti Andresen — Thu, 19 May 2016 12:12:44 GMT

No, but it is a good idea, I have created a case including my latest changes. Thank you for your input.

P.S. As expected fitting a shield above the sensitive clock line seems to have eliminated the noise.

RE: nRF52832 32HMz HF clock noise / EMI issues

run_ar — Thu, 19 May 2016 07:44:16 GMT

Have you considered creating a support case on mypage? If you upload your HW files our HW engineers can take a look at your layout to check the design.