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TMS570LC4357: Unused pins

Archana Rao
Intellectual 915 points
Part Number: TMS570LC4357

Hi,

We are using TMS570LC4357 in our design.

We are not using ADC and few other interfaces.

Can these be left unconnected?

The datasheet says the unused IO pins can be left unconnected since they have internal pull up/pull downs.

There are few pins which do not have any internal pull up/pull downs.  Can these pins also be unconnected if unused?

Regards,

Archana Rao

  • 0
    TI__Guru**** 196776 points

    Hello Archana,

    Unused I/O pins can be left unconnected. ADCIN pins can be left open too if they are not used. ADCREFHI and ADCREFLO need to be connected to VCCAD and GND even if ADC is not used. These are reference voltages for the ADC.

  • 0 in reply to QJ Wang
    Intellectual 915 points

    Hi Wang,

    Thank you for your valuable reply.

    If ADC interface is not used, can VSSAD/ADCREFLO be connected to digital ground?

    Also, had another query.  If there are non-I/O pins, such as CAN and SPI interfaces, can these also be left unconnected if not used?

    Somehow, datasheet does not give much description for unused pins.  Or am I missing something?  Please correct us.

    Regards,

    Archana Rao

  • 0 in reply to Archana Rao
    TI__Guru**** 196776 points

    Hello,

    For input only or output only digital signals with internal PU or PD, you can leave those signals unconnected. CAN and SPI signals are I/O signals. If there is analog GND, connect VSSAD/ADCREFLO to the analog ground. If the digital and analog share the same GND, just connect VSSAD/ADCREFLO to GND.