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ADS803-Driving inputs with fully differential op

Guillermo Pocetti
Prodigy 150 points
Other Parts Discussed in Thread: THS4503, ADS803

Hello,

Is there any issue in driving the ads803 inputs differentially with a fully differential (say THS4503) op instead of a transformer?

Thanks,

Best Regards

  • 0
    TI__Mastermind 29220 points

    Hi,

    No, there is no problem doing that.  In fact, that is probably the most straightforward case of using an amp.  I think the datasheet focuses on the single ended examples because those are the cases where a customer would then want to know how to bias the unused input on the ADC and so we put those examples in the datasheet.  But using a fully differential amp is fine - just meake sure the signal into the ADC has a common mode voltage of about 2.5 V.  Either use the common mode input pin of the amp if it has one to set the amp common mode output to 2.5V, or if the path out of the amp is AC coupled then spliting the load resistor into two resistors with a 2.5V connection at the center will bias the signal to 2.5V.

    Regards,

    Richard P.

  • 0 in reply to Richard Prentice
    Prodigy 150 points

    Hi,

    Thanks for your answer. Another question ... How is the best way to interface this AD with a microcontroller, since It doesn't have any syncro signal such as "convertion done"? I was thinking of using an external clock provided by a crystal oscillator for the AD and then connect it also to a GPIO of the microcontroller and use it to syncronize with the AD, that is to say, read data of the parallel output everytime there is a rising edge (by interruption) of the clock (taking into consideration the 6.5 clock cycles of data latency and the new data delay time).

    PD: As it is a pipeline architeture, would you recommend it for a high resolution ultrasonic distance measurement ??

    Thank you very much,

    Best regards

  • 0 in reply to Guillermo Pocetti
    TI__Mastermind 29220 points

    Hi,

    I see you've created a new post for this question so I have responded there.

    Regards,

    Richard P.