• State TI Thinks Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 1 answer
  • Subscribers 13 subscribers
  • Views 341 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ISO6540: Isolation products vs Ground-level translator products

Ed Hann
Prodigy 20 points
Part Number: ISO6540
Other Parts Discussed in Thread: TXG4041, , ISO6740, ISO7740, ISO6441

Tool/software:

I need voltage level translation product that also provides 12V of isolation between the A and B sides of the IC. Currently looking at the ISO6540 vs the TXG4041 or 8041.

The desire is to provide some level of insulation between the sides of the IC in case of a power supply overvoltage failure on the other side.

It appears that the two families are essentially the same technology with the ground-level translators having a lesser SiO2 insulation barrier. Is this a fair assessment?

Also does the SiO2 barrier protect one side of the IC from I/O or power overvoltage on the other side?

  • 0
    TI__Mastermind 18745 points

    Hi Ed,

    Thanks for reaching out.

    The ISO6540 is a digital isolator that is recommended for functional isolation. This means that the isolator is guaranteed to provide signal integrity against ground loops. Both the TXG4041 and ISO6540 are not full rated for overvoltage transients in relation to system safety and protection. both offer functional safety. the main difference is that the ISO6540 is designed to be an isolator for higher ground potential differences, meaning that it may protect against higher levels of ground loop interference over the TXG4041 device.

    Ed Hann said:

    The desire is to provide some level of insulation between the sides of the IC in case of a power supply overvoltage failure on the other side.

    Since you mentioned the above, it seems like you are looking for a digital isolator that is rated for basic or reinforced isolation, which means that it is rated for a certain level of safety in relation to failures that could occur in your system. Good options for isolators as described above are listed below. Since you had mentioned 4 channel device, I have included the 4 channel digital isolators that are rated for reinforced isolation:

    1. ISO6740 (Various channel configurations): This digital isolator supports 100Mbps and has various supply voltage options
    2. ISO7740 (Various channel configurations): This digital isolator supports 100Mbps and has various package options
    3. ISO6441 (Various channel configurations): This is our latest generation of digital isolators, supports up to 150Mbps

    I would also like to mention that all of the digital isolators mentioned above can act as level translators as well. 12V isolation requirement across either side of the isolator is definitely possible with the above options.

    Regards,
    Aaditya V

  • 0 in reply to Aaditya V.
    Prodigy 20 points

    Thank you for the reply.

    I would like to add a little more clarity to our situation.

    The isolator uses a common ground on both sides and converts 3V logic to 1.8V logic. Note that we currently use the 74AVC4T774 which provides no protection for this failure.

    The concern is if our 1.8V buck regulator fails and allows the output to go to 12V battery voltage. This will destroy the 1.8V side of the part, but the goal is not to damage the processor connected to the 3V side. That means limiting current from the 1.8V side to the 3V side should the failure occur (ground currents are OK). 5000V isolation barrier seems like overkill for 12V stress across the barrier.

    I like the ISO series of parts except for the power consumption. We have a battery-powered product. That was the primary motivation for the TXG family.

  • 0 in reply to Ed Hann
    TI__Mastermind 18745 points

    Hi Ed,

    Thanks for your response. Please allow us an additional day to look into this.

    Regards,
    Aaditya

  • 0 in reply to Aaditya V.
    TI__Mastermind 18745 points

    Hi Ed,

    Sorry for the delay and thank you for the patience.

    Thank you very much for the background and information. I understand your reasoning for considering the ISO6540 for your application. AS I mentioned before, the ISO65xx family of digital isolators are functional digital isolators, meaning that we can only guarantee that they allow for signals to be accurately transmitted between side 1 and side 2 without interference from the ground loop difference. However, it seems that your application requires protection between side 1 and side 2 when a possibly power supply failure occurs, causing 12V to directly supply one side of the isolator. Considering this, the ISO65xx family does not guarantee this level of protection, hence my previous suggestion of our reinforced isolators.

    Our reinforced isolators are characterized for providing the protection against transients and overvoltage events, unlike the functional isolators such as ISO65xx. These devices also maintain the isolation of side 1 and side 2 depending on the failure mode (Understanding failure modes in isolators (Rev. B)) and can allow for the protection of side 2 in case there is an overvoltage or transient event that damages side 1. 

    Understanding isolator failure modes for safe isolation - Shorter description with images.

    I hope this clarifies my recommendation in regards to using a reinforced isolator for the application you have specified. Please let me know if you have any additional questions!

    Regards,
    Aaditya V