Because of the holidays, TI E2E™ design support forum responses will be delayed from Dec. 25 through Jan. 2. Thank you for your patience.

  • State TI Thinks Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 3 answers
  • Subscribers 46 subscribers
  • Views 3322 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

ADC 4-20ma and 0-10V

Brian Cavanagh97
Prodigy 190 points
Other Parts Discussed in Thread: ADS1120, ADS8681, ADS8668, ADS8664

Hi, can someone suggest an ADC that's cost effective that reads 4-20mA and/or 0-10Vdc?

The application will never have both 4-20mA and 0-10Vdc working at the same time, they will choose between either one.

I'll be talking to this chip via SPI.  The power rail will be 12Vdc with a 5VDC that will power the IC's.

Sample rate of 2kSPS is fine along with being 12bit.  I'm not sure if the input type needs to be differential for the 4-20mA circuit or not.  I know for sure I will not have any NEGATIVE rails.

Thank you,

Brian

  • 0
    TI__Mastermind 22315 points
    Hi Brian,

    welcome to our forum. You might want to have a look at our ADS1120. That would be a great fit.
    You would have to use a resistor divider to divide the 10V signal down to within the range of the internal 2.048V voltage reference.
    For the current input you could use a <=100Ohm shunt.

    Regards,
  • 0 in reply to Joachim Wuerker
    TI__Intellectual 1130 points

    Hi Brian

    In addition to Joachim's recommendation of ADS1120, you can also look at ADS8668 (8-ch), ADS8664 (4-ch) and ADS8681 (1-ch) devices. You would need an external shunt for the 4-20mA input but the devices can handle 0-10V with a single 5V supply rail. In case you need, there are multiple other input ranges that can be configured via SPI and the ADS866x devices also have a pin-compatible 14/16/18 bit versions for a future upgrade.

    Please let us know if you have any further questions.

    Thanks

  • 0 in reply to Vinay Agarwal
    Prodigy 190 points
    I like this Vinay. I can use AIN_0P / AIN_0GND for my 4-20 (using the shunt of course), but also just put my 0-10VDC signal to AIN_1P with AIN_1GND tied to ground? That would be great!
  • 0 in reply to Brian Cavanagh97
    TI__Intellectual 1130 points
    Absolutely you can .. you can use the ADS8664 and use the two channels in the way you have described. The ranges for each channel can be configured independent of each other.

    Thanks