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CC2340R5: Is it safe to left the SWCLK and SWDIO pin open for CC2340?

Shuyang Zhong
Expert 4410 points
Part Number: CC2340R5

Tool/software:

My customer has found that CC2340's power consumption unexpectedly high on some of their boards. If these 2 pins are pulled up, the power consumption was back to normal. I read from the TRM that a minimum of 100kohm resistance is recommended by ARM, but CC2340 already has internal pull-up/pull-down resistors on SWD pins.

My question is if the internal pull-up/pull-down resistor strong enough for the design? Is it recommended to add external pull-up/pull-down resistors on the board, or it is OK to left them open?

Best regards,

Shuyang

  • 0
    TI__Expert 6520 points

    Hi Shuyang,

    The internal pull-up would be stronger than a 100k external resistor. If you look at the relevant section of the data sheet you can see the pull current:

    Compare that to what would be provided by a 100k pull resistor. So I wouldn't expect that an external pull resistor would be required.

    How are these pins being configured by software? Is the internal pull being removed? is the pin being reconfigured as an input? If needed you can also submit a request for a schematic review (https://www.ti.com/tool/SIMPLELINK-2-4GHZ-DESIGN-REVIEWS)  so we can see if we can identify any other possible sources for the issue.

    Thanks,

    Jake

  • 0 in reply to Jake Pulliam
    TI__Expert 4410 points

    Hi Jake,

    Thanks for the reply. The customer's issue turned out to be caused by another reason, not the pull up resistor. Thanks for making it clear for the internal pull up resistor question.

    Best regards,

    Shuyang