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TMS570LS0432 ADref

Johan Deben
Intellectual 655 points
Other Parts Discussed in Thread: TMS570LS0432

Can we put ADFREFHIO (VccAD) at zero volt during standby or operation?

Is this allowed?

  • 0
    TI__Guru 68920 points

    Johan,

    Which pin?  ADREFHI and VCCAD are different pins.

    The spec ranges for these are in the device datasheet - which device are you asking about?

  • 0 in reply to Anthony F. Seely
    TI__Mastermind 49120 points

    You can also power down the ADC in software. This reduces the current consumption from the VCCAD and ADREFHI supplies to less than 5uA under nominal operating conditions.

    The TRM describes the procedure to power down the ADC core.

  • 0 in reply to Anthony F. Seely
    Intellectual 255 points

    Anthony;

    For TMS570LS0432; VCCAD and ADREFHI share same pin.

    So; if I use a voltage refence, the voltage reference will also used as VCCAD supply.

    But I could not find a current requirement for VCCAD in the datasheeet.The datasheet states 45 mA  for a combined consumption of I_CCAD,I_CCIO and I_CCP.

    Then do i need a 45mA capable voltage reference ?

    Thank you

    Regards.

  • 0 in reply to Hakan AVCI
    TI__Guru 68920 points

    Hakan,

    Good point, I didn't catch that.
    Yes you will need to provide at least 45mA.

    The question about whether or not you need a 45mA reference I suppose depends on your sensor scheme.

    If the sensor is able to be powered by and provide a value that is proportional to the LS0432's power rail then a separate reference might not be required.

    If not then I suppose you could either find a reference that can power 45mA, or alternatively use a lower power reference on a dedicated ADC input channel (say set to 3.0V) and sample this channel 'almost simultaneously' with your other inputs,  then scale the result.   More math and relies on sequential sampling being 'fast enough' but might cost less.