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Operation of the ADS9110EMV

Tom Campbell
Prodigy 70 points
Other Parts Discussed in Thread: ADS9110, ADS8678, THS4551, THS4521

We are only able to record a peak measurement of 65,300 ADC (~2.245 V) with the ADS9110EMV development unit.

We have verified that our detector is putting out voltages, depending on our test condition, of up to 9 V.

Why are we seeing this regular limitation to 2.245V??

It was my understanding that the ADS9110 would handle up to 4.7 V.


Do we need to put an amplifier in front of the ADS9110?  If so, can you provide the instructions and device details.

Before we proceed in ordering the ADS8678, we need to understand the dynamics between the single ended output from our detector and the input to the TI product.  SMA coax RG-174 to SMA coax interconnect.  Signal input to J7.  J4 is jumpered from 1 to 2.  J1 and J2 have no jumpers.

Thx,

Tom Campbell 805-377-1690  tcampbell@airware-inc.com

  • 0
    TI__Guru 55466 points

    Hi Tom,

    The ADS9110 has a fully-differential input; where both negative and positive inputs swing between 0 and VREF.  The evaluation board does not support single-ended signals. The external source must be differential or balanced keeping the negative and positive inputs to the board symmetric such that Vs(+) = –Vs(–) at any given time; and the source needs to be able to drive the 1kOhm input impedance.  The ADS9110EVM board as configured accepts fully-differential signals with 3 common-mode options:  0 V, 2.25 V, and floating with jumpers J1 and J2.  Since the detector is producing single-ended signals, a single to differential conversion stage is required prior driving the EVM or ADS9110.   

    Can you please provide a schematic, datasheet or diagram of the detector?  Is the detector producing a single-ended signal?  What is the common-mode and amplitude range, frequency characteristics of the signal you need to support?   What resolution do you require in this application?  

    The ADS9110 is a high performance, 2MSPS, 18-bit fully-differential input SAR ADC, requiring a driver amplifier front-end and external reference driver circuitry.  It supports unipolar differential range +/- REF (REF 2.5V to 5V)

    The ADS8678 is a 14-bit SAR ADC with 8 channels mux, integrating a PGA front end, reference, supporting bipolar and unipolar independently programmable inputs and analog low pass filter set to 15kHz.  

    Thanks and Regards,

    Luis

     

  • 0
    Prodigy 70 points
    Dear Luis:
    Schematic & datasheet - this is an InGaAs detector with a transimpedance amp and TE cooler with a single coaxial output. No schematic as this is a proprietary module.
    Yes, the detector is producing a single-ended signal.
    Common-mode? and amplitude range is 0 to ~9V , we are operating between 10kHz and 100kHz frequency.
    Looking for 1ppm resolution goal for our application, but we are taking what we can get for now?
    Can you provide details on a differential conversion stage?
    Thx,
    Tom
  • 0 in reply to Tom Campbell
    Prodigy 70 points

    Dear Luis:

    I was able to find an LT6350 low noise, single-ended to differential converter/ADC driver with a fast settling time, but it will only support 0-4 V.  Does TI have a low noise, fast settling time differential converter to handle 0-10V?

    Thx,

    Tom Campbell

  • 0 in reply to Tom Campbell
    TI__Guru 55466 points

    Hi Tom,

    We offer the THS4551 and the THS4521 fully-differential amplifiers that can allow you to perform single-ended to differential conversion and drive the ADS9110.

    I will look into simulations for the optimal RC filter and resistor selection for your application; and get back to you with more details within the next couple of days.

    Many Thanks,

    Kind Regards,

    Luis

  • 0 in reply to Luis Chioye
    Prodigy 70 points
    Dear Luis:

    Thank you for the THS4551/4521 suggestion.

    Since I now have an expert, how about a recommendation on an 18-bit or higher ADC, SAR preferred (but Sigma Delta would be considered) with with a pseudo-bipolar input with ability to handle a 0-10V input range that we can obtain as part of a demo kit?

    Rgds,
    Tom
  • 0 in reply to Luis Chioye
    TI__Guru 55466 points
    Hi Tom,

    I will contact you and follow up with this information directly via email.

    Thank you,

    Kind Regards,
    Luis