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Appropriate Chip/evaluation kit for electrophysiological signal acquistion

Chris French
Prodigy 70 points
Other Parts Discussed in Thread: ADS1248EVM-PDK, ADS1298ECGFE-PDK, ADS1298, ADS7280, ADS7230, ADS8330, INA333, TINA-TI, ADS8363EVM

Apologies for basic question, but had difficulty working through all the possibilities on the TI site

I have been wanting to build an A/D converter for electrophysiological signals (pre-amplified to arbitrarily useful voltages such as +-5V) with the following basic specs - at least 14 bit resolution, and minimum of 500k samples/second (1million preferred); minimum of 2 channels, 4 preferred, but happy to run a set of single channel chips in parallel; D/A capabilities also very useful. Power is not an issue; lowish noise is good. The ADS1248EVM-PDK looks interesting; reasonably simple software interface would be useful, perhaps to be run from Matlab, but can code in C etc. Evaluation kit much preferred.

Could I get some suggestions?

Many thanks

Chris French, University of Melbourne

  • 0
    TI__Guru**** 180771 points

    Hi Chris,

    Welcome to the e2e forum!  Have you taken a look at the ADS1298 and/or the ADS1298ECGFE-PDK hardware yet? 

  • 0 in reply to Tom Hendrick
    Prodigy 70 points

    Tom

    Thanks for the suggestion. It looks excellent, but the sample rate is a bit low (32 kSPS).  Anything comparable with faster sample rate? I would emphasise that although it's for electrophysiology, its actually for cells in a dish, so clinical compatability is not a problem.

    Thanks again

    Chris French

  • 0 in reply to Chris French
    TI__Expert 3260 points

    Hi Chris,

    What are your system requirements? What kind of sample rate are you looking to achieve (interested max)? Specifications of interest?

  • 0 in reply to Michael W
    Prodigy 70 points

    Hi Michael

    I record from cells using an amplifier that filters and amplifies to give a suitable voltage range for digitisation, in the 1-10 V range, so no problems with signal level as such. What I need is a decent dynamic range, so 12 bits would be a minimum, but 14 or more is desirable. The actual experiments I do tend to be "episodic", ie sampling 10-20 episodes between 10 and 10000 ms at intervals of 1-20 seconds, although occasionally continuous acquistion is helpful. I need different time resolutions for different experiments- I typically record at 10 microscends/point, but this is faster than I really need. However, in some particular experiments 1 microsecond (or if not practical, 2-4 microseconds)/point is necessary. Power is not a problem. The other issue is how to get the data into a reasonable file format, but I suppose that is not so important to start with.

    Additionally, I routinely record 2 channels with one DAC to provide voltage commands to the amplifier, so 2 channels of input is needed, either in a single chip or two chips in parallel.

    Many tahnks

    Chris French

  • 0 in reply to Chris French
    TI__Expert 3260 points

    Hello Chris,

    We have a few parts that may fit your needs. ADS7230, ADS7280, or ADS8330. But, I would caution you on the signal conditioning circuitry boosting the input signal up to 10V. This is going to greatly limit the number of devices to use. These suggested devices fit the other requirements you have, but do not allow for up to 10V input voltages.

  • 0 in reply to Michael W
    Prodigy 70 points

    Michael

    Thanks for the suggestions; the chips look good; as I was interested in getting an evaulation board for the project, I found I also found http://www.ti.com/tool/ads8363evm for the 8363 chip - do you think this would be ok? The input voltage is not a problem - I can scale it from the input amplifier to any range needed; I think some signal conditioning would be useful for other purposes - notch filter, maybe some autoscaling - do you have any suggestions for this?

    Many thanks

    Chris French

  • 0 in reply to Chris French
    TI__Guru**** 180771 points

    Hi Chris,

    Have you ever looked into TINA-TI?  This is a free tool from Texas Instruments and Design Soft that allows you to simulate various analog design scenarios which might suit your particular application.  Take a look at the INA333 - this data sheet (available from the link provided here) includes links to various TINA-TI circuits which you may find useful.

  • 0 in reply to Tom Hendrick
    Prodigy 70 points

    Hi Tom

    Thanks for that - I have ordered the ads8363evm and will definitely have a look at this tool.

     

  • 0 in reply to Chris French
    Prodigy 70 points

    Tom

    I've got the neat ads8363evm board - I was wondering if  there was something like the TSW1200EVM interface board for this to help interfacing software/hardware?

    Thanks

    Chris French

  • 0 in reply to Chris French
    TI__Guru**** 180771 points

    Hi Chris,

    Unfortunately no, the TSW1200 is not compatible with the ADS8363EVM.