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Circuit configuration for QFN73 And QFN48 for the NRF52840

Techist

Dear Professionals ,

I have series of questions to ask concerning the circuit configuration of the QFN73 And QFN48 for the NRF52840 as shown in the documentation site  https://docs.nordicsemi.com/bundle/ps_nrf52840/page/ref_circuitry.html .

According to the information found in documentation site the QFN package is of two types; the QFN73 And QFN48 packages.

Question 1: Which circuit configuration is best suited for the following between the QFN73 And QFN48 packages:

  • Battery (3.7V 5000MAH) Powered. We intend to drop the 3.7V to 3.3/3.4V for the NRF MCU.
  • 2 UARTs peripheral
  • 1 ADC 
    NOTE (No usage of USB. We will flash the board via SWD.)

Question 2: QFN48 package seem compact, since it has less pin count. Does it supports 2 UARTs? I couldn't find the UART pinout on its documentation.

Question 3: Can you please break down these conditions of the QFN48 package for me please, I found them in the attached link above:

  • High Voltage supply mode cannot be used because the VDDH pin is not routed in the QFN48 package.
  • The external supply feature cannot be used because the VDDH pin is not routed in the QFN48 package.
  • DCDC for REG0 stage cannot be used because the VDDH pin is not routed in the QFN48 package.
  • USBD cannot be used because the USB pins are not routed in the QFN48 package.

Thank you!

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  • 0

    Hi,

    The main difference would be the package it comes in, so either 48 or 73 pin option for QFN.




    You can read all about the pins of each package type here: https://docs.nordicsemi.com/bundle/ps_nrf52840/page/pin.html 






    Question 1: Which circuit configuration is best suited for the following between the QFN73 And QFN48 packages:

    Any of the configs will work, but since you are using 3.3V then you can select any of the normal voltage mode configs. 






    Question 2: QFN48 package seem compact, since it has less pin count. Does it supports 2 UARTs? I couldn't find the UART pinout on its documentation.

    UART can be done on any of the GPIO's so that is not a problem. The QFN48 still have many GPIO to use so that should not be a problem. 




    Question 3: Can you please break down these conditions of the QFN48 package for me please, I found them in the attached link above:

    All the note's here are due to no VDDH pin on this package variant. 




    You can use QFN48 package type, there we only have 1 Config, This should be ok for you since you are not using USB or VDDH. 



    We do schematic and layout reviews so when you have something designed we can have a look at it and provide feedback.  This can be done in a new private ticket.



    Regards,
    Jonathan

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  • 0

    Hi,

    The main difference would be the package it comes in, so either 48 or 73 pin option for QFN.




    You can read all about the pins of each package type here: https://docs.nordicsemi.com/bundle/ps_nrf52840/page/pin.html 






    Question 1: Which circuit configuration is best suited for the following between the QFN73 And QFN48 packages:

    Any of the configs will work, but since you are using 3.3V then you can select any of the normal voltage mode configs. 






    Question 2: QFN48 package seem compact, since it has less pin count. Does it supports 2 UARTs? I couldn't find the UART pinout on its documentation.

    UART can be done on any of the GPIO's so that is not a problem. The QFN48 still have many GPIO to use so that should not be a problem. 




    Question 3: Can you please break down these conditions of the QFN48 package for me please, I found them in the attached link above:

    All the note's here are due to no VDDH pin on this package variant. 




    You can use QFN48 package type, there we only have 1 Config, This should be ok for you since you are not using USB or VDDH. 



    We do schematic and layout reviews so when you have something designed we can have a look at it and provide feedback.  This can be done in a new private ticket.



    Regards,
    Jonathan

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