nRF52840 SOM hardware review

RE: nRF52840 SOM hardware review

Ping — Thu, 26 Sep 2019 01:47:24 GMT

Hi Andreas，

Get it，thanks for your suggestion and review.

Best regards

Ping

RE: nRF52840 SOM hardware review

Andreas — Wed, 25 Sep 2019 12:22:46 GMT

Hi,

I am just bringing you an answer in Kajas absence.

2. There should be should be similar capacitance on both pins, for a CL=8 pF crystal this should be approximately 12 pF.

3. This is fine, these antennas should not need any matching, as you have C57, C54 and C2 you should be covered if the via or somethinc causes mismatch.

Overall the layout looks very good. There is good grounding and you have replicated our recommendations through the reference layout.

Best regards,

Andreas

RE: nRF52840 SOM hardware review

Ping — Wed, 25 Sep 2019 02:00:41 GMT

Hi Kaja

Thank you for your support.

2. The load capacitance is 12pF +10pF, muRata 10pF(100) ±2% 50V GJM1555C1H100GB01D and 12pF(120) ±2% 50V GJM1555C1H120GB01D

3. We use the IPEX RF connector to connect the external antenna,The antenna can be customized according to the product structure. we can use Soft plate PCB antenna , such as Taoglas FXP74 2.4GHz http://www.taoglas.cn/zh/product/black-diamond-fxp74-2-4ghz-flex-pcb-antenna/ or Taoglas GW.17 2.4GHz Terminal Antenna http://www.taoglas.cn/product/gw-17-2-4ghz-terminal-antenna-ipex-mhf/

Best reagards

Ping

RE: nRF52840 SOM hardware review

Kaja — Tue, 24 Sep 2019 13:58:48 GMT

Hi Ping,

here is the feedback:
1. C14 must be 100 nF
2. The matching network for the radio has the values: C5 = 0.8 pF, L1= 4.7 nH and C6= 0.5 pF, these values must be tuned for the specific design.
2. What is the load capacitance, CL, of the crystals you are using?
3. What antenna are you using?

I will give you more feedback on the layout when I know what antenna you are using.

Best regards,
Kaja