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DAC80508: Reference Voltage Range

Shinichi Yokota
Genius 9715 points
Part Number: DAC80508

Hello,

DAC80508's data sheet has an item REFERENCE INPUT in the section 7.3 Recommended Operating Conditions, but are the specs applied to only external reference input VREFIN or both external and internal VREF?

The word REFERENCE INPUT reminds me of external reference voltage.and I'm wondering if it's applicable to only external or both.

Best regards,
Shinichi Yokota

  • 0
    TI__Guru 52743 points

    Hi Yokota-san,

    The internal reference is only and always 2.5V, so there is really no limits that need to be applied to it.  The minimum VDD supply of 2.7V still allows the internal reference to operate at 2.5V.  An external reference needs to be limited to be within the range of the power supplies and there is a minimum reference input voltage that is required for the DAC to operate.  In summary, the VREFIN portion of the REcommended Operating Conditions table really applies to the external reference input. 

    Thanks,

    Paul

  • 0 in reply to Paul_Frost
    TI__Genius 9715 points

    Paul,

    Thanks for your quick feedback.

    Then, I'm wondering why 1b is read from the REF-ALM bit in the STATUS register under the following configuration.

    • VDD = 3.5 V
    • Internal VREF (always 2.5 V)
    • Output gain: ×2
    • Reference divider: ÷1

    Do you have any hint or suggestion?

    Best regards,
    Shinichi Yokota

  • 0 in reply to Shinichi Yokota
    TI__Mastermind 25923 points

    Hi Yokota-san,

    With a 3.5 V VDD you will need to enable the reference divider even when using the internal reference because it is greater than 3.5V/2 (VDD/2).

    Best,

    Katlynne Jones