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TLV56xx: Difference AVDD - DVDD?

Brian Anderson
Prodigy 175 points
Other Parts Discussed in Thread: TLV5608

Regarding DACs from the TLV56xx family (e.g. TLV5608): From a forum post I learned that AGND and DGND are internally shorted. How about AVdd and DVdd? Unlike for ADCs, the data sheets do not state if AVdd and DVdd may be different, for instance DVdd = 3.3V and AVdd = 5V. Would that be allowed?

Thank you - Brian

  • 0
    TI__Expert 6925 points

    Hello Brian,

    It is perfectly fine to have different voltages for AVDD and DVDD, and 3.3V digital and 5V analog is a typical setup as long as all grounds form the TLV56xx and the power supplies are tied together. 

    Just keep in mind that the voltage in digital inputs should not exceed DVDD.

    BTW, the reference input voltage should be less than or equal to AVDD. 

    Regards,

  • 0 in reply to Rafael Ordonez
    TI__Guru**** 180821 points

    Hi Brian,

    Keep in mind as well that AGND and DGND are not always tied together internal to the ADC or DAC.  You need to ensure those nodes stay within +/-300mv of each other.  This is usually accomplished by tying both pins to a common ground plane very near to the device.

  • 0 in reply to Tom Hendrick
    Prodigy 175 points

    Hi Tom,

    well, I read somewhere else in this forum that AGND and DGND are tied together internally in the TLV56xx devices. I am of course happy if it is not required to tie these grounds together in the DAC- my star point is somewhere else- of course, we do not expect such high differences in the potentials, but a few mV could occur...

    Brian

  • 0 in reply to Rafael Ordonez
    Prodigy 175 points

    Hi Rafael,

    thanks a lot- I know from the ADC datasheets that DVDD is also specified with regard to AVDD and vice versa- this statement is missing in the TLV56xx datasheets. So, thank you for clarification :)

    Brian