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ISO7741: ESD protection measures coming from SPI-I / F

cafain
Mastermind 6425 points
Part Number: ISO7741

Hi,

ESD protection measures coming from SPI-I / F

The device of SPI interface is corrupted by ESD.
* Since the SPI interfaces with the external device, it is connected to the connector.

Please tell me the best solution for ESD protection measures.
I am considering the following two methods.

1. Use digital isolation to protect the device from ESD from the SPI.
　　※ Please introduce the device of digital isolator suitable for SPI.

2. Connect the protection diode of ESD (TVS) to the signal line.
    ※ Please introduce ESD device suitable for SPI.

best regards
cafain

  • 0
    TI__Expert 6195 points

    Hi Cafain,

    Thanks for bringing your question about isolated SPI to us.

    I would recommend looking at the Digital Isolator Design Guide. Section 2 talks about Typical Applications for Digital Isolators and Isolated Functions. If you look on figure 5 on page 5 you can see an example of an Isolated SPI Interface. 

    For a specific part, I would recommend the ISO7741 for isolated SPI. It is a high performance, quad-channel digital isolator. It can handle up to 100Mbps and has a wide signal range of 2.25V to 5.5V, so I think it should work great in your application. Figure 22 of the ISO7741 datasheet (page 26) show an isolated SPI interface. ISO774x devices have been significantly enhanced to ease system-level ESD, EFT, surge, and emissions compliance. You can check out the ISO7741 ESD ratings in section 6.2 on page 6 of the ISO7741 datasheet. 

    Let me know if that answers all of your questions!

    Best regards, 

    Dan

  • 0 in reply to Dan Kisling
    Mastermind 6425 points

    Hi, Dan-san

    I appreciate the precise advice.
    I will consider ISO7741 as a reference.

    It is a confirmation、
    System level tolerance is written in datasheet 8.3.1, but has it actually passed the specifications of IEC 61000-2, IEC 61000-4?

    best regards

  • 0 in reply to cafain
    TI__Expert 6195 points

    Hi Cafain-san,

    IEC61000-2, IEC 6100-4 is a system level test so just a device cannot be certified. We have optimized the device for EMC performance.  

    We do have an application note on Low-Emission Designs With ISOW7841.

    To see the certifications we have received check the Technical Documents tab on the product folder.

  • 0 in reply to Dan Kisling
    Mastermind 6425 points

    Hi, Dan-san

    I appreciate the detailed and prompt support.
    I will evaluate whether it can protect from ESD in ISO 7741.

    Thank you very much.

    cafain