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CC2640R2F: MCU getting powered from UART pins.

YSR1991
Intellectual 420 points
Part Number: CC2640R2F


Hello All,

II am using CC2640R2F from scanning BLE tags and sending data to other MCU.

While testing, i have observed that CC2640R2F resetting after some interval.

I have removed power signals of CC2640R2F while testing, but still its working, only UART pins from other controller which is powered.

So MCU is getting powered from UART pins only, (power pins not connected to 3.3V supply)

So please guide in this regard.

Regards,

Sharad.

  • 0
    TI__Guru**** 317180 points
    -"I have removed power signals of CC2640R2F while testing, but still its working": Meaning that the circuit is still able to scan tags? It should not be possible to power the circuit from the UART pins to my knowledge.
    - Is this a custom board? If that is the case, we most likely should take a look at schematic/ layout.
  • 0 in reply to TER
    Intellectual 420 points

    Thanks TER for reply.

    I have attached schematic image of my custom board. Please check. 

    When VDDS is disconnected, then also CC2640R2F remains powered. And in this case it resets continuously.

    Regards,

    Sharad.

  • 0 in reply to YSR1991
    TI__Guru**** 317180 points
    I would it get reset due to the BOD. If you only remove the VDDS it's probably some leakage through ESD diodes

    I assume the chip is grounded with a lot of vias from the die paddle to ground.

    You wrote:
    "While testing, i have observed that CC2640R2F resetting after some interval."

    "I have removed power signals of CC2640R2F while testing, but still its working"

    Why do you remove power when testing? Please check the max rating for the chip. Do you always remove power while testing?

    If you have powered the board as intended during testing, could you please measure VDDR to see if this is above 1.6 V?