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ADS8555: ADS8555 HVDD and HVSS settings

Marco Di Sciuva
Prodigy 85 points
Part Number: ADS8555

Hello,

could you please let me know the correct value for ADS8555 supply voltages HVDD and HVSS.

If I use the internal VREF (2.5V) with input range of +/- 2*VREF, can I use supply voltages 5V +/- 5%

and -5V +/- 5%, considering tht the real input value range is +-4V?

If I use an external reference, for example 1.5V, with input range of +/- 2*VREF, can I use supply voltages

of +/-3V?

Thanks.

Marco

  • 0
    TI__Mastermind 35520 points

    Hi Marco Di Sciuva,

    If you can make sure that your real input will not exceed the power supplies, +/-5V can be used as your power supplies. Note that the specification in the data sheet were characterized with HVDD=10 to 15V and HVSS=-15~-10V supplies.

    For your external reference example, you can use +/-3V as power supplies if you can guarantee that the supplies have no tolerance and will not be lower than +/-3V . Otherwise, the linearity may be affected.

    Thanks&regards,

    Dale

  • 0 in reply to Dale Li
    Prodigy 85 points

    Hi Dale,

    I have to manage signals with +/- 3V range and I was thinking to use an 1.5V external reference for ADS8555 configurated in +/-2*Vref option.
    I'd use a supply voltage +5V (5% tol) for HVDD and -5V (5% tol) for HVSS.
    Do you think it could work?
    What does it mean with "the specification in the data sheet were characterized with HVDD=10 to 15V and HVSS=-15~-10V supplies"?
    Out of this range the ADS8555 specifications are worst?

    Thanks.

    Marco

  • 0 in reply to Marco Di Sciuva
    TI__Mastermind 35520 points

    Hi Marco,

    I apologized for late response because I had troubles to log on and check the forums during the trip of passed two weeks.

    The external reference voltage range accepted by ADS8555 is from 0.5V to 3V, so your solution to use 1.5V external reference should work.

    These conditions are specified in the Electrical Characteristics table of the datasheet, which means the performance shown in this table were characterized under these conditions. The specifications and performance may be different or worse when the test conditions are out of the ranges..

    Thanks&regards

    Dale