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Device suggestion for long distance application

Jacky Chen29
Genius 4735 points
Other Parts Discussed in Thread: ADS1014, ADS7042, ADS1015, TCA4311A

Hola,

We would like to use ADS1014/5 for long distance(about 5 meters) application to detect voltage(5V & 3.3V),

for this long distance I2C transmission with different voltage level application, does TI have any device can

be recommended？Thanks ～

  • 0
    Genius 4735 points
    Hola,
    Can someone help to reply this？ Thanks ～
  • 0
    TI__Intellectual 1610 points

    Hello,

    Thank you for your query. Can you please look into this device? http://www.ti.com/product/TCA9406

    Regards,

    Krunal

  • 0
    TI__Intellectual 1205 points

    In my opinion, measuring a voltage with any kind of precision over that great of a distance could prove to be problematic regardless of which ADC you choose.

    Without very much detail on your application, there are at least three solutions:

    1.  Have you considered using one of TI's XTR-series devices to convert your voltage to a current at the source?  Driving a current over 5m is no problem, as you will get the same current out the other end of the cable (assuming leakage is negligible).  Driving a voltage will result in voltage drops proportional to the length of the cabling. TI has a line of current-input ADC's.  If they are not what you want, you can always convert back to a voltage on the measurement end.

    2. At the very least, you will need a buffer amplifier at the measurement end to minimize IR drops.  That way, you can get the most accurate measurement possible given the conditions. 

    3. Use an ADC that is small enough to place at the voltage end.  Your digital communications will have to be transmitted over the 5m of cable, but digital signals inherently reject noise.  Take a look at the ADS7042.  It is the smallest, lowest power 12-bit SAR ADC you can get.  The only problem is that it can only go up to AVdd = 3.6V, so you would have to do some scaling in order to measure your 5V signal.


    In any case, you should be able to find an ADC at the following link that will complete your design.

  • 0 in reply to Bryan McKay
    Genius 4735 points

    Hola Krunal & Bryan,

    Thank you for the prompt reply. After discussion and we plan to use the item-3 which is Bryan's suggested before.

    To place a ADC nearby the power detect side and then to transmit to the MCU with long distance.

    We plan to use 4 channel for current design and will extend to 16 channel in the future.

    ADS7042 seems only 1 channel and used SPI interfac, we need to use a lot of IO for LED signboard application.

    Original we plan to use ADS1015 with I2C for long distance transmission, may I know that does TCA4311A is a suitable solution

    to do the long distance transmission with 3V power supply？ Thanks ～

  • 0 in reply to Jacky Chen29
    Genius 4735 points

    Hola,

    After discussion and we plan to use the item-3 which is Bryan's suggested before.

    To place a ADC nearby the power detect side and then to transmit to the MCU with long distance.

    We plan to use 4 channel for current design and will extend to 16 channel in the future.

    ADS7042 seems only 1 channel and used SPI interfac, we need to use a lot of IO for LED signboard application.

    Original we plan to use ADS1015 with I2C for long distance transmission, may I know that does TCA4311A is a suitable solution

    to do the long distance transmission with 3V power supply？ Thanks ～

  • 0 in reply to Jacky Chen29
    Genius 4735 points
    Can someone help to reply this urgent issue？Thanks ～
  • 0 in reply to Jacky Chen29
    TI__Intellectual 1205 points

    In order to provide any kind of recommendation, could you provide some details about your application? 

    What are you trying to measure?  How many channels?  How are you connecting it to an ADC?  What voltages are available for analog, digital, and reference supplies?  What type of interface?  What kind of measurement accuracy are you looking for? What kinds of things are important for your design (speed, power, accuracy, ...)?

    The more details we have, the better we can provide recommendations.

  • 0 in reply to Bryan McKay
    Genius 4735 points

    Hola Bryan,

    We will place ADC nearby the power detector and long transmission to the MCU.

    4 channel is enough for our current design and will extend to 16 channel in the future.

    Below is out application to detect 4.5V/3.3V power module and ADS1015 12bit should be enough.

    電源偵測_0729.pdf