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  • Case ID: 286106
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PCB Design with nRF52840 SoC

user111909

Hi,

First of all thank you for your support and suggestions.

As I am planning to use nRF52840 SoC in my design, (Project: BLE based Environmental sensor). The circuit mainly consist of the sensor (uses SPI), Battery Circuit, Antenna (Mostly U.FL Connector), nRF52840 SoC. Is there any similar PCB design template projects available in order to refer?

Reference Circuit: Nordic Semiconductor Infocenter

Also I have found some points which are not familiar to me, 

  • Power supply: It found from the datasheet that use of DC/DC Regulator has san advantage on Current consumption. (USB is not included in my design) can I go with Circuit configuration no 5 for QIAA aQFN73 (by connecting VBUS to GND) in order to get advantages of DC/DC Regulator?
  • If so, can I design the entire circuit with 3V Battery power supply?
  • Regarding antenna, I would like to do design with U.FL Connector (easy to go with external Antenna), Can I follow the same ANtenna circuit provided in the reference circuit provided in product specification? (or is there any special design required?
  • If I am using only some GPIO pins specially for SPI communication, is it fine to make all other unused pins to float or unconnected?
  • How External Crystal oscillator helps my design in terms of power consumption?( I found HFXO helps in reducing current consumption) Is it recommended to use external clocks?
  • There are some capacitors (C10, C13..) which are mentioned as Not Mounted (NC) on the Bill of Material of the reference circuit. What it indicates? Do I need to avoid these capacitors from my design?

I am really interested and looking forward for  valuable suggestions and resposnes. I really do appreciate your help, time and effort.

Thanks and Regards,

Sreejith

  • 0 in reply to user108933

    Hi Kazi,

    so helpful! 

    leaving the C13 unconnected, cause DEC2 pin to be unconnected (float). Is that fine? or does you mean connecting DEC2 pin to ground without capacitor (C13)?

    Is this is the same scenario for C9 (it is mentioned that it is not required for Fxx and later but I could not get it)?

    Altogether, leaving N.C (Non mounted capacitors) means, makes the pins floating (un connected) or remove the component (Capacitor) and shorten the path ?

    Thanks and would like to hear from you,

    Sreejith 

  • 0 in reply to user111909

    Hello Sreejith,

    Yes C13 and DEC2 pin to be unconnected. No you do not need to ground DEC2. It is same for DEC5 as well. 

    Thanks. 

    Feel free to ask if you have more questions. 

    Best Regards,

    Kazi Afroza Sultana

  • 0 in reply to user108933

    Hi Kazi,

    Thanks for your guide!I am hereby closing this ticket. Thank you for your time!

    best Regards,

    Sreejith

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