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DAC121C085: VA and VREF for optimal noise performance

Alan Islas
Prodigy 60 points
Part Number: DAC121C085

Hi, 

Is there an advantage in noise performance of connecting VA and VREF to the same supply? 
Any ratiometric advantage of having those two supplies being the same and hence moving together?

Or is the noise performance solely based on how clean VREF is? The datasheet seems to point to this case, but wanted to confirm and hopefully get some more insight. 

Thanks!
Alan

  • 0
    TI__Mastermind 29468 points

    Hi Alan, 

    You are interpreting the datasheet correctly. Since the DAC121C085 has separate supply and reference pins, the VREF supply is what is going to dominate the noise performance. VREF is what determines the output voltage of the DAC that is fed to the input to the output buffer. So any noise on VREF will be seen directly on VOUT. The supply is just powering the buffer and other circuitry in the device. There wouldn't be a benefit for VREF and VA to move together ratiometrically. 

    Best,

    Katlynne Jones 

  • 0 in reply to Katlynne Jones
    Prodigy 60 points

    Hi Katlynne, thanks for your reply and confirmation, it is very useful!

    Regards, 
    Alan