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TMP1826: ESD Recommendation for SDQ Bus

Part Number: TMP1826
Other Parts Discussed in Thread: AM2431, ESD351

Hi Team,

we are going to use TMP1826 with AM2431 in bus powered mode.

Between the GPIO of AM2431 and SDQ in of TMP1826 we have up to 25m cable.

Please can you recommend the ESD protection diode on the TMP1826 side and on the AM2431 side?

Also would you recommend  a RC filter or a ferrite bead on the AM2431 side ? 

Or do you maybe have a reference design with TMP1826 and ESD protection?

Best Regards,


  • Hello,

    The TMP1826 internally includes 8-kV IEC-61000-4-2 ESD protection on the data pin.  Are you expecting that you will need further ESD protection?  

    We do, of course, offer ESD protection devices as well, which can be found below.  Let me know if you can provide a further description of your ESD requirements and I can look for specific devices.  At this time, we do not have a reference design which includes additional ESD protection.;11.99 

  • Hi Eddie,

    we decided to go with ESD351DPY for additional ESD protection and EFT + surge protection that the TMP1826 doesn't provide internally: 

    IEC 61000-4-2 Level 4 ESD Protection

    – ±30-kV Contact Discharge

    – ±30-kV Air Gap Discharge

    • IEC 61000-4-4 EFT Protection

    – 80 A (5/50 ns)

    • IEC 61000-4-5 Surge Protection

    – 6 A (8/20 µs)

    Also i added a series 100R 

    Please let us know your comments.

    Best Regards,


  • Hello d.

    In general, the ESD351DPY looks like a good part to add additional external ESD protection up to 30kV.  

    The placement of the 100 ohm series resistor should also be considered.  If the series resistor is between the pull up and the device, this will cause some additional voltage drop.  If you are operating at lower voltage, such as 1.8V, this could be an issue, especially if there are multiple devices on the bus.  

    If the series resistor was placed between the host MCU and pull up, there should not be an issue.  

    Would you be able to share your schematic and I can give it a check?   If you do not want to share publicly, let me know and we can email.

  • Hi Eddie,

    The system is 3.3V, and i got the 100R from SLUU244A , they are using it.

    Maybe we should go with smaller resistance like 10R.

    eg i found a single wire device protection from maxim DS9530 that has an integrated esd diode + resistors ,but the resistors are only 5Ohm.

    So my thought was either using DS9503 or ESD351 + 10R or 100R resistor , what do you think? 

    I provided the schematic , the SP9 is connect to connector and after that is the R1 and D1 ant then U1.



  • d.,

    Yes, these solutions should work.  Of course, I recommend the TI solution.  The 10ohm resistor is more likely appropriate.