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nrf 51822 change Tx power from +4dBm to -20dBm how much power can it save?

Hi all,

Anyone has tried if the Tx power of nrf 51822 is changed from +4dBm to -20dBm, how much power (%) can it save, in a ballpark figure?

Thank, Carl

  • Hi

    The peak currents in the different power modes are specified in the nRF51822 datasheet in table 36 and 37 on page 50-51.

    As you can see there is quite a large difference between -4, 0 and +4 dBm output power, but below -4 dBm you are seeing diminishing returns, and I wouldn't normally recommend going below -4 to save power.

    It is important to keep in mind that the TX peak current is only a small part of the total power budget, once you add in the RX current, CPU processing, radio startup, peripherals and so forth.
    This is protocol and application specific, so if want to get an accurate estimate you have to figure out how large portion of your average current is contributed by the TX for your application.

    Best regards
    Torbjørn

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