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MSPM0L1105: Protect button inputs

Francisco Fernandez
Prodigy 140 points

Part Number: MSPM0L1105

Hi. We are considering the migration from a 8 bits MCU to the MSPM0L1105 32 bits MCU.

We need to connect several pushbuttons to the GPIOs of the referred part number and I would like to know if you have any recommendations that should be followed with this type of MCU. Currently we control the pushbuttons with VCC and use an external pulldown resistor on each MCU input.

1. Would you recommend to keep using the mentioned aproach?

2. Would it be neccesary to use a TVS as ESD protection?

3. Would you recommend using the internal pulldown resistor?

Thanks

  • 0
    TI__Mastermind 46765 points

    HI,

    1. Your method looks fine for me. 

    2. Yes, if you are looking for a higher ESD level. 

    3. You can use the internal pulldown resistor as long as you do not exceed the current limitation on the device datasheet. 

    Best regards,

    Cash Hao

  • 0 in reply to Cash Hao11
    Prodigy 140 points

    Thanks Cash Hao,

    Related to the current limitation of the device, can you confirm that each IO can only sink/source only 6mA? This is question is related to the connection of LEDs without a transistor, directly to an output of the MCU. If I tie together two outputs and activate them at the same time, would I be assured to have 12mA sourcing/sinking capability?

    I want to double check this question because it seems few mA compared to other devices that I have used in the past.

    Thanks

  • 0 in reply to Francisco Fernandez
    TI__Mastermind 46765 points

    Hi,

    Yes, each GPIO can sink/source below 6 mA. In theory, it is possible to tie two outputs together to get 12mA. However, I do not recommend to do that. You can use the ODIO to achieve that which sink current is 20mA.

    Best regards,

    Cash Hao