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ISO124: Application doubt

Mohit Mahajan
Prodigy 10 points
Part Number: ISO124
Other Parts Discussed in Thread: ATL431LI, , ISO224

I wanted to use ISO 124 to obtain an isolated analog output for an analog input. I have a doubt that can the supply be 18V/12V and 0V at Vs1+,Vs2+ and Vs1-,Vs2- respectively or is it required to supply +18V/+12V and -18V/-12V respectively. In the datasheet it is mentioned that the absolute max rating of Vin pin is 100V so can I give an input of 0-18V or 0-12V in the input or as mentioned in the description I have to give a 0-10V input. 

ISO124 - Functional Diagram         

  • 0
    Guru 317370 points

    The recommended operating conditions table says that you need to use split power supplies. If you have only a single supply, you can generate a virtual ground; see Single-Supply Operation of Isolation Amplifiers for examples (but replace the Zener with the ATL431LI), or simply use a voltage divider and an opamp.

    The absolute maximum ratings tell you what voltages you can use without destroying the device. They do not guarantee that the device actually works. The ISO214 needs a headroom of about 5 V to the power rails, so if you decide to split the +18 V supply into −5 V/+13 V, then you can handle signals between about 0 V and 8 V.

    What is your application? Where does the input come from, and what is its actual voltage range? What supplies do you have available?

  • 0
    TI__Guru**** 181021 points

    Hi Mohit,

    Welcome to our e2e forum!  Clemens is correct, you need to supply at least -5V for the negative rails of the ISO124.  Please also take a look at the ISO224, which can run from single 5V supplies on the user and high sides.