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ISO224: Isolation design

Martin Grinfeld1
Prodigy 85 points
Part Number: ISO224

Tool/software:

For our  new  project, we need the electronics that comes into contact with the patient being treated to be isolated from other components of the medical device. The isolation voltage should be 5KV or higher. The signals to be isolated are:

  1. Digital control signals, +3.3V, with frequency lower than 5 KHz.
  2. Output voltage +/- 4V max, frequency lower than100 Hz

Can you recommend a component to implement point 1?

Can point 2 be implemented by the ISO224? Do we need to  provide positive and negative power supplies on both the isolated and the non isolated sections of the ISO224?

Thank you 

Martin Grinfeld

  • 0
    TI__Expert 4010 points

    Hi Martin,

    Martin Grinfeld1 said:
    Digital control signals, +3.3V, with frequency lower than 5 KHz.

    For digital signals, you can use a digital isolator.  You can take a look at the digital isolators here.  These parts are handled by another team, and I can re-assign this thread to them or you can create a new thread to ask questions.

    Martin Grinfeld1 said:
    Can point 2 be implemented by the ISO224? Do we need to  provide positive and negative power supplies on both the isolated and the non isolated sections of the ISO224?

    The ISO244 will need a separate supply for each side of the isolation barrier.  Can you describe the signal you are trying to measure a little more?  What is your input signal coming from, and after it crosses the isolation barrier what will be reading it?

    Thanks.

  • 0
    Prodigy 85 points

    Thank you Saleh Ahmad for your prompt reply. Regarding your question, the input signal to  the isolator amplifier is a multiplexed,  time sliced signal of multiple T-type thermocouple sensors each of which monitors the patient's body temperature at different locations. The voltage range of the thermocouple sensors is -20 mV to +20 mV. After the amplifier -4V to +4V. Please see the picture attached.

  • +1 in reply to Martin Grinfeld1
    Prodigy 85 points

    My question is:

    Can we get the full voltage range, -4V to +4V, by suppling only positive supply voltages to the ISO224?

    I prepared a picture depicting the circuit (JPG file) although I don't see a way to attach it. Can I email it to you?

  • 0 in reply to Martin Grinfeld1
    TI__Expert 4010 points

    Hi Martin,

    I'm assuming the following E2E is related and answering on there. 

    e2e.ti.com/.../iso224-power-supply-for-iso224

    Thanks.