• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 47 subscribers
  • Views 582 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Need help finding the right part for my customer with AutoScan type of feature

Kent Kunzler
Prodigy 120 points

Other Parts Discussed in Thread: ADS8568, ADS8332, ADS8344, ADS8345, ADS8363, ADS8556, ADS7263, TLC3541, ADS7279

My customer is looking for a 16Bit ADC with the following features:

  • at least 500KSPS
  • 8 channels
  • serial interface
  • auto scan feature- He wants to be able to pick any channel at any point in time to read the latest result from that channel.  Would he need a part with 8 individual ADC's, or is there another part that will automatically scan through each channel?

 I recommended the following parts to him, is the ADS8568 the only part that will do the Autoscan feature that they are looking for?

ADS8332: 2.7V-5.5V, 16 Bit 500KSPS Low Power Serial ADC, 8-Ch MUX and Breakout
Product Folder: http://focus.ti.com/docs/prod/folders/print/ads8332.html
Data sheet (PDF): http://focus.ti.com/lit/ds/sbas363b/sbas363b.pdf

ADS8344: 16-Bit, 8-Channel Serial Output Sampling Analog-to-Digital Converter
Product Folder: http://focus.ti.com/docs/prod/folders/print/ads8344.html
Data sheet (PDF): http://focus.ti.com/lit/ds/sbas139e/sbas139e.pdf

ADS8345: 16-Bit, 8-Channel Serial Output Sampling Analog-to-Digital Converter
Product Folder: http://focus.ti.com/docs/prod/folders/print/ads8345.html
Data sheet (PDF): http://focus.ti.com/lit/ds/sbas177c/sbas177c.pdf

ADS8568: 16-Bit, 8-Channel, Simultaneous Sampling, Bipolar Input ADC
Product Folder: http://focus.ti.com/docs/prod/folders/print/ads8568.html

ADS8363: 16-bit 1MSPS 4x2/2x2 Simultaneous Sampling SAR ADC
Product Folder: http://focus.ti.com/docs/prod/folders/print/ads8363.html
Data sheet (PDF): http://focus.ti.com/lit/ds/sbas523b/sbas523b.pdf

ADS8556: 630kSPS, 6-Channels, Simultaneous Sampling Analog-to-Digital Converter
Product Folder: http://focus.ti.com/docs/prod/folders/print/ads8556.html
Data sheet (PDF): http://focus.ti.com/lit/ds/sbas404a/sbas404a.pdf

Please advise,

 

Kent Kunzler

Seltec Sales Corporation

  • 0
    TI__Guru**** 182521 points

    Hi Kent,

    The ADS8568 actually simultaneouslysamples all eight inputs by means of four CONVST inputs - the speed of this part in serial mode is 480KSPS, but that is actually 'per channel' assuming you are using the four serial output option.  Samples are taken by channel pair (CHAx, Bx, Cx and Dx) in this device and each channel pair can have its data presented on its own serial output pin.  All conversion results can also be directed to SDO_A with reduced throughput.

    The ADS8332 will auto scan through the selected inputs - you can also manually command a specific channel.  The 500KSPS rate is assuming you are continuously sampling one channel.  To scan through all eight, the effective throughput is 500K/8 or 62.5KSPS/CH.

    The ADS8344 and ADS8345 are only 100KSPS devices and these are both strictly command byte driven to change the input MUX address.  They don't 'auto scan' by themselves however the software setup is relatively simple to make them work in a sequential mode.

    The ADS8363 has two internal ADC's and two muxes.  These also work in pairs (CHAx and CHBx) also with simultaneous sampling capability.  These parts have two serial outputs to take data from the A channel and B channel separately, or you can combine all data outputs and send everything through the SDOA pin.  This device does offer a sequencer option that would provide paired channel conversion results.

    The ADS8556 is similar to the ADS8568 in its operation - the main difference here is six versus eight channels.  These two parts also feature a bipolar input up to +/-12V.  The other three parts above have an input range of 0-5V.  So, if you need bi-polar, the ADS8568 may be the part you want to focus on.  The ADS8332 though is probably going to have the channel selection flexibility you are looking for. 

  • 0 in reply to Tom Hendrick
    Prodigy 120 points

    Thanks Tom, this answers the customers questions!

     

    Kent

  • 0 in reply to Tom Hendrick
    Prodigy 120 points

    Tom,

    My customer has changed their requirements on this design, and I need your help to narrow down the right part. 

    Here are some recent conversations with him:

    1. Upon further review I think a 14-bit ADC will work. Per the pp presentation I’m going to take a look at TI’s ADS7263, 8557 and 8548.

    2. Oh and another thing, I don’t need simultaneous sampling like these parts are. So I guess I’ll be looking at ADS7279, 7871, 7890, 8324, TLC3541, 3545, 3548 and 3578

    3. Can be anything 50Ksps or better

    4. Must be serial interface
    5. 8 channels
    6. They are looking at a +/- 200V signal that they will scale down so that the ADC can read. 
      • Measurement resolution <100mV
      • Accuracy +/-2% of reading
    7. Another input will be the following:
      • Input range +/- 100mVDC
      • Measurement resolution <50uV
      • Accuracy +/-2% of reading
    8. Yet another input will be the following:
      • +/- 10VDCMeasurement resolution- can be scaled down if necessary
      •  <50mVAccuracy
      • +/-2% of reading
    9. They are concerned about very good DC performance, and things like linearity, and offset error are very important.

    Let me know what we should propose at this point.

     

    Best regards,

     

    Kent