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ECG defibrillator resistor

david sun77114
Expert 2162 points

Other Parts Discussed in Thread: ADS1298

I have a design using VR6800001003JAC00 as defibrillator protection resistor in ECG front end circuit. but this is a through hole part and very big. could any one suggest a surface mount resistor. is there a standard specify the requirement of this resistor? thanks.

 

 

  • 0
    TI__Guru**** 183061 points

    Hi David!

    Hopefully someone on this forum who's used the ADS1298 in a production capacity can give you a little insight to an appropriate device/part number to replace your VR68xxx.  We don't have any information to share on parts that might be qualified for your specific end equipment.  A good place to start would be with your local testing agencies that would qualify your end product as an approved Medical/Clinical/Sports(Fitness) device. 

  • 0
    Prodigy 200 points

    Hello David,

      Have you got replacement for VR6800001003JAC00 part in SMD package?

    If yes, please let me know the replacement part.

    What is the ideal voltage rating required for defib protection.

    Thanks,

    Sachin Nalbalwar

  • 0 in reply to Tom Hendrick
    Prodigy 15 points
    I have a general question regarding defibrillation. I don't seem to have seen anything done "correctly", in that it would meet the requirements of IEC 60601-1. I am looking at figure 9 (see 8.5.51) pg 78 Application to the test circuit a shown in Figure 10. blah blah blah.

    I don't think I can put a screen capture in here - no, it didn't work.
    But I simulated the circuit in spice, and the minimum value of pure resistance that passes the test is about 133k. all patient connections but one are connected to return and the one is connected to a 5kV pulse.

    I see circuit with 20k or 50k in series with the input to a channel (clamped of course). Even if you only have 2 channels, one to return and one to 5kV, that is too low a value of resistance to pass.

    Are all of these reference doc's and EKG circuit I see in TI application notes and elsewhere only for making devices that do EKG, but not real medical devices that could be sold (at least not in the US or in Europe) ?

    Everyone addresses whether their input protection circuitry protects the circuit, but never any mention whatsoever of whether the circuit complies with FDA / IEC requirements.

    Can anyone explain this? I don't think my simulations are wrong.

    Regards,
    John
  • 0 in reply to John Fitch
    TI__Mastermind 38745 points
    Hello John,

    If I remember correctly, the standard requires that some percentage of the energy delivered by the defibrillator go through the patient. My interpretation of energy is power (current x voltage) x time. In the past I have run some simulations and was able to meet this specification. Can you say how much energy is being absorbed by the defibrillation circuit versus the patient?

    To attach a picture to e2e posts, clock "Use rich formatting" in the lower right and then there should be an option to attach an image from your file system.

    Brian