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ISO7741: Creepage and Clearance of Isolation IC

Victoria Qin
Intellectual 980 points
Part Number: ISO7741

Hi team,

Good day!

Recently I'm learning TI isolation products. I would like to know more specific documents about some conceptions.

  1. About creepage and clearance, I understand the conception on IC. And bigger package allows higher isolation capabilities. How can I promote ICs with suitable creepage and clearance? Are there documents explaining clearance and clearance more detailed?
  2. I would like to know the phenomenon when capacitive isolation barrier is broken down.
  3. Is there international standard to define and differentiate basic isolation and reinforced isolation? So I could promote suitable isolation level to customers.
  4. Optical isolation is limited by LED turn-on speed in high speed data application. I would like to know the data rate boundary separating optical isolation, magnetic isolation and capacitive isolation.

Looking forward to your kind reply.

Thanks.

Victoria

  • +1
    TI__Genius 14160 points

    Hello Victoria,

    Thanks for your questions. Glad to hear you are learning about our isolation products and how to promote them. I've answered your questions in order below.

    1. Yes, your understanding is correct, the package size is related to the creepage and clearance of the device. Are you asking how to determine what creepage and clearance value is suitable for a specific application? The necessary creepage and clearance for a given application is largely dependent on the industry standard for that specific use case and what level of isolation is required. There is a video on TI precision labs that explains creepage and clearance, you can access it here.

    2. When the capacitive  isolation barrier is broken or damaged this means that the insulation of the barrier has begun to breakdown, usually due to a voltage outside of the device's specs being applied. In the event that the isolation barrier is broken entirely, there will no longer be any isolation, which could potentially damage equipment and present a danger to users of the system. 

    3. There are a handful of standards that define different levels of isolation. If you ever need to know what standards a specific TI isolator is certified to, you can check the "Safety Related Certifications" section in the specific device's datasheet and the actual certifications for a specific device can also be found under the technical documentation section of the product folder on TI.com. When it comes to basic vs. reinforced isolation the IEC 60747-17 standard is the one to refer to. Please note that this is a component level standard and there may be additional system level standards to consider for different applications.

    4. The data rate boundaries are not strict cutoffs so it is always best to verify the supported data rates of specific isolators in their respective datasheets. The data rates will depend on the specific technology and device being used. In general you can achieve higher data rates with both magnetic and capacitive isolators but it is not the same with optical.

    If you haven't reviewed them already, the Isolation Frequently Asked Questions page on E2E has many common questions and useful resources/trainings collected in one place, which may be useful as you continue to learn more about our isolation products. You can access the FAQs here. If you have any other questions please feel free to reach out again!

    Regards,

    Darrah