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DAC8760 external Referance

Sarper ONAL
Prodigy 130 points
Other Parts Discussed in Thread: DAC8760, TS5A3160

Hello,

I like to use external reference voltage for DAC8760 to get different output scales. What we deserve to get is max bit count on +-0,5V, +-1V, +- 1,5V, +-2V, +-4V for this reason I like to use different external references, maybe changeable ones by a program. 

Best Regards.

  • 0
    Prodigy 130 points
    Is there any table that shows the output scale interms of external reference
  • 0
    Prodigy 130 points
    Actually better question could be this; I like to switch between internal referance and external referance, is that possible?
    Internal referance is 5V, I like to use 2.5V external referance to acheive 16 bit on +-2V and +-5V output voltage stages. And then programatically change it to internal referance to acheive +-10V stages.
  • 0
    Prodigy 130 points

    I like to use external reference and internal reference simultaneously with user input from the program. So I like to use a switch between internal and external reference (1ohm max TS5A3160 from TI) 

    Do you think this approach is suitable for the DAC8760 REFIN pin? If you advise me I will be appreciated. 

    Basically, The Normally Connected pin of a TS5A3160 is connected to the REFIN pin directly, so normally system works with internal reference. If we like to use +-2V output we change internal reference to external 2V reference by the MCURefControl pin.



  • 0 in reply to Sarper ONAL
    TI__Genius 11750 points

    Howdy Sarper,

    I'm currently looking into to you posts, and will try to answer the posts shortly and before COB.

    Best Regards,
    Matt

  • 0 in reply to Matthew Sauceda
    TI__Genius 11750 points
    Howdy Sarper,

    I've read through the datasheet and verified that the acceptable input voltage of REFIN is from 4.95 to 5.05V. This information is described in the "Recommended Operating Conditions" of page 5 of the DAC8760 datasheet. The intrinsic design of the DAC8760 device requires this specific range in biasing certain internal structures, and any deviation from this range may result in unexpected behavior and operation. In datasheets, the "Recommended Operating Conditions" are included to communicate the recommended conditions for correct operation.

    I would suggest using a an operational amplifier at the DAC output in a difference configuration to achieve the voltage output ranges desired. You can then set the gain by adjusting the value to a few passive components, but please be aware that the op amp and passives will add to the error of the system, therefore select components that fit the accuracy goal of your application.

    If you have any other questions please let me know.

    Best Regards,
    Matt
  • 0 in reply to Matthew Sauceda
    Prodigy 130 points

    Howdy Matthew,

    Thank you for your answer, I will try to find another way to implement +-0.5V +-1V and +-1,5V and also +-2V on 16Bit

    Best Regards. 

  • 0 in reply to Sarper ONAL
    TI__Genius 11750 points
    Hi Sarper,

    Thanks for the response and using the e2e forums.

    Best Regards,
    Matt