Hi, I have run some tests on the LP-MSPM0G3507 EVM board. And I get the same conclusion as yours. If there is any pull down resistor on the RX pin. MCU will consume more power in this situation. And actually, the idle state of the UART TX and RX pin is logic high. Adding pull down resistor on the TX/RX pin will indeed consume more power. It does not make sense to add this pull down resistor from my side. About adding the pull-up resistor on the UART TX/RX pin, there is some use cases which may need it. While the microcontroller is in reset, its I/O pins will be configured as high-impedance inputs. So the pin used for a UART serial Transmit Data (TXD) will be floating during this time. This can lead to noise causing rubbish to be transmitted. A pull up resistor can avoid this this. I also tested using the internal pull up resistor, it will not cause extra current consumption to the MCU. Customer can add this feature if they need it. Best regards, Cash Hao
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