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ADS1241: Does it have a faster sps version?

Kenny Yip
Prodigy 70 points
Part Number: ADS1241
Other Parts Discussed in Thread: ADS1216, ADS1235, ADS1217, ADS1218

Hello!

I found this ADC good!.  It has the DAC inside to cancel the DC portion from the strain gauge output.  Then I can amplify the AC part by the PGA.  This seems fit my application.  

However, for the conversion speed, I can only find the "fdata".  It is 15 Hz max.  Is it the SPS?

I need 500 sps.  If this is not applicable, do you have some other part numbers that has this sampling rate?

And here is my comment to your product search.

I could not find ADS1241 in this page https://www.ti.com/data-converters/adc-circuit/precision-adcs/products.html#p84=20;10000&sort=o1;asc

And it is difficult for me to find your ADC that has DAC and PGA >= 128.

Thank you so much!

Kenny

  • 0
    TI__Guru** 113765 points

    Hi Kenny,

    Unfortunately the data output rate is limited on the ADS1241.  I would recommend looking at other devices without the ODAC as there are other ways of handling a dc offset.  The ODAC is limited to 8 bits, so you may not get as good of a result as you might expect.  However, as similar device is the ADS1216 that has a faster data output rate and also includes an offset DAC.

    It is not totally clear how you are intending to use the ADC.  You may want to take a look at a device that is newer and offers some additional capabilities.  For example, the ADS1235 offers the ability to use ac excitation for bridge applications. 

    The ADS1235 can also be calibrated to remove system offset.  For example, if you are measuring strain in a bidirectional fashion and want to remove any dc offset, you could issue the SYOCAL which will calibrate your system to a 24-bit level instead of 8-bit level using the ODAC.

    Best regards,

    Bob B

  • 0 in reply to Bob Benjamin
    Prodigy 70 points

    Thanks Bob!

    The ADS1216 is good.  Seems fits my application!

    The signal I am measuring is a AC pressure on top of a DC pressure (not constant).  I wish to make something like the AC coupling of the scope in order to amplify the AC part as much as possible.

    I found that there are the ADS1217 and ADS1218 with similar architecture.  Would you tell me the difference between them if you have the information on hand?  Otherwise I can find them out from the datasheets.

    Thanks for introducing the AC excitation to me.  May try this later.  

    Thank you!

  • 0 in reply to Kenny Yip
    TI__Guru** 113765 points

    Hi Kenny,

    The ADS1217 and ADS1218 are very similar to the ADS1216.  The FSR range of the ADS1216 is +/- VREF/PGA, and the ADS1217 is +/- 2VREF/PGA.  The ADS1218 includes a FLASH memory storage area.

    The overall signal must stay within the input range of the ADC, which is bounded by the analog supply voltage.  So even if you adjust the dc offset, you most likely will not see any improvement in the ac performance relative to the peak to peak value of the ac waveform as the maximum gain is 128.  All you will essentially do is move the mean of the signal.  The mean can be removed by calculation.

    Your biggest benefit would be by achieving the lowest possible noise from the measurement.  Here you would benefit by using one of the devices I mentioned in my previous post.

    Best regards,

    Bob B