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CC2640R2L: Power consumption in Standby Mode with enabled peripherals

Patrick Vögeli
Prodigy 60 points
Part Number: CC2640R2L

Hi,

We've created a custom board using the CC2640R2L and some other peripherals connected over SPI. This part is battery powered, so Power Consumption is very relevant.

The SPI communication is working as expected and I can put the devices into its low power states (with power consumptions rated below 5 µA). However, we've measured our power consumption when everything is in Low Power to be over 200 µA.

After doing some tests, I've seen that I can lower my Power Consumption if I disable the UART (using UART Display for some debugging outputs) & I close the SPI Communication. In this case, my power consumption goes to around 80 µA.

Looking in the Power Consumption Summary of the CC2640R2L Datasheet, I can see the currents taken by the peripherals: UART =164 µA &SSI = 93 µA, but there's also the note "Iperi is not supported in Standby or Shutdown).

From my understanding, SPI & UART should not affect my Standby consumption. Do you have any comments on this? Is this the expected behaviour?



Thank you and best regards,

Patrick

  • 0
    TI__Guru**** 217617 points

    Hi Patrick,

    As you've noted, the device is still in Standby Mode since the current consumption is more than 650 µA which would indicate idling in Active Mode.  As indicated by the datasheet, peripheral current is not applied in low power modes, furthermore UART and SPI peripheral consumption combines to be more than the difference observed.  What you are seeing is most likely the leakage current of input pins associated with these peripherals when an instance is opened, like for UART RX and SPI MISO.  This typically assists in waking the MCU to service an interrupt upon reception of data from a connected device.  If you do not require such features, then perhaps it would be possible to disable/close these peripherals during periods where no activity is expected.

    Regards,
    Ryan

  • 0 in reply to Ryan Brown1
    Prodigy 60 points

    Thanks Ryan, it seems you were right and when the pins are setup, there's some leakage current.

    As a workaround, I'm disabling the UART & SPI when no activity is expected.

    Best regards,

    Patrick