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ADS114S08: Universal Sensor input support through ADS114S08

Dhvanish Parekh
Prodigy 90 points
Part Number: ADS114S08
Other Parts Discussed in Thread: ADS124S08

Currenlty I am working on one Analog sensor based project and looking to provide support of different analog sensors through one ADC.

We have reviewed ADS114S08 datasheet and reference circuits, based on that have queries as below:

  1. I have sensor with output range of 0-5V. Does this ADC support 5V input on ADC channels (when I set AVDD=5V, Vrefp = 5V & Vrefn = 0V) ? Or will require any different configurations?
  2. It is showing “Preproduction” and Status as: “Preview” for ADS114S08 part variants. Kindly provide information on its availability and lead time. (http://www.ti.com/product/ADS114S08/samplebuy)

Thanks,

Dhvanish Parekh

  • 0
    TI__Mastermind 21765 points
    Dear Dhvanish Parekh,

    thank you for your interest in our new ADS114S08. This device is a perfect fit to measure all kinds of different sensor signals.

    1. Yes, you can measure sensor signals ranging from 0V to 5V when you use AVDD=5V, AVSS=0V, REFP=5V and REFN=0V. But you need to set the Gain=1 and bypass the PGA in this configuration to get the rail to rail input capability.

    2. The ADS114S08 in the TQFP package (PBS suffix) is active and in production already. You will also see a 'Request free sample' button showing up within the next few days. Standard lead times apply of about 6-8 weeks. If you order from the TI Store you should actually be able to get material within a few days. The QFN package version (RHB suffix) will release soon as well.

    Regards,
  • 0 in reply to Joachim Wuerker
    TI__Mastermind 21765 points
    Dear Dhvanish Parekh,

    I just wanted to let you know that the 'Request Sample' button shows up on the product folder now and that you can now order the ADS114S08 in the TQFP package from the TI Store.

    Regards,
    Joachim
  • 0 in reply to Joachim Wuerker
    Prodigy 90 points

    Thank you Joachim for the response!

    Also, I want to understand few things related to isolation:

    1. Yes! It is showing sample request enabled. Also, I noticed that both ADS114S08 & ADS124S08 are pin-to-pin replaceable. Kindly confirm
    2. I reviewed "tidrkm5.pdf" schematic and found that it has provided digital & power isolation to Analog section in the design. Any specific reason behind that? As far as I understood, it is provided for noise & to avoid any malfunction on digital side due to sensor error.

    Thanks,

    Dhvanish Parekh

  • 0 in reply to Dhvanish Parekh
    TI__Mastermind 21765 points
    Dear Dhvanish Parekh,

    yes, you are correct. The ADS114S08 and ADS124S08 are pin-to-pin and also functional compatible. The only difference is the word length of the conversion result.

    In PLC analog input modules or many other sensor measurement systems such as field transmitters, galvanic isolation is usually used to break ground loops, but also to protect humans or the PLC backplane from high voltages.
    The ADC itself does not require a digital isolator for proper operation as long as the GND of the host MCU and the ADC are at the same potential. This is more of a system requirement.

    Regards,