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LM63615-Q1: Looking for a TVS for use in a 24V system

taeyun kim
Prodigy 10 points
Part Number: LM63615-Q1
Other Parts Discussed in Thread: TSD24-Q1

Tool/software:

Hi team

I'm planning to use the LM63615DQPWPRQ1 in a 24V system. Please recommend a suitable TVS for IC protection
  • 0
    TI__Genius 11495 points

    Hi Taeyun,

    1. is this a 24V automotive system?

    2. What is the input voltage range? 

    3. Do you have any particular ISO pulses that you are planning to protect your system against? 

    Thanks,

    Best Regards,

    Taru

  • 0 in reply to Taru Kapoor
    Prodigy 10 points

    1. No, this is not a 24V automotive system. It is a general commercial AC/DC power supply system

    2. input voltage range is 24V+-5%(22.8V~25.2V)

    3. We are using the power supply coming into the factory and aim to comply with the EN 61000-6-2 and EN 61000-6-4 standards. Therefore, I understand that it is necessary to protect against pulses with 1.2/50 µs and 8/20 µs waveforms

    Thanks,

    Best Regards,

    taeyun

  • 0 in reply to taeyun kim
    TI__Genius 11495 points

    Hi Taeyun,

    I have asked our TVS Diode Product Line to help give you a recommendation here. They'll get back to you. 

    Thanks,

    Best Regards,

    Taru

  • +1 in reply to Taru Kapoor
    TI__Expert 6070 points

    Hi Taeyun and Taru,

    It sounds like TSD24-Q1 might be a good option here. 24V working voltage, 30kV IEC 61000-4-2 and 9A IEC 61000-4-5. This device also clamps below 40V, which will protect the LM63615-Q1 voltage pin (which has an absolute maximum of 40V).

    Please let me know if there are any additional questions here!

    Best Regards,

    Josh Prushing

  • 0 in reply to Josh Prushing
    Prodigy 10 points

    The TSD24-Q1 datasheet does not include information about the 10/1000 µs waveform. Can we ignore the specifications for this pulse?
    Is it not necessary to protect against both the 10/1000 µs waveform and the 8/20 µs waveform?

  • 0 in reply to taeyun kim
    TI__Expert 6070 points

    Hi Taeyun,

    Both the 10/1000µs and 8/20µs waveforms depict surge waveforms, but the 10/1000µs is more strenuous compared to the 8/20µs. Is there a 10/1000µs surge rating requirement you need to meet? 

    taeyun kim said:
    3. We are using the power supply coming into the factory and aim to comply with the EN 61000-6-2 and EN 61000-6-4 standards. Therefore, I understand that it is necessary to protect against pulses with 1.2/50 µs and 8/20 µs waveforms

    10/1000µs was not listed in original requirements, so I just wish to confirm the target value for either 8/20µs or 10/1000µs surge rating.

    Best Regards,

    Josh Prushing

  • 0 in reply to Josh Prushing
    Prodigy 10 points

    Hi Josh

    It cannot be stated definitively that protection against the 10/1000µs waveform is required, but isn't it possible that surges with both 10/1000µs and 8/20µs waveforms could occur together? If that is the case, I thought a method to protect against both waveforms might be necessary.
    When designing using TVS, what criteria are usually used?

    Best Regards,
    Taeyun

  • 0 in reply to taeyun kim
    TI__Expert 6070 points

    Hi Taeyun,

    While technically possible that surges with both of these waveforms could occur together, you can often identify which transient you are more likely to face based on the power in your system. 10/1000µs has a much higher power, and is used to model surge currents in situations like load dump scenarios. 8/20µs is used to model coupled surge from nearby power lines and longer transients.

    In most situations, it is acceptable to design for one or the other. If you design for 10/1000µs, you will have the capability to protect against the 8/20µs transients. If you design for the 8/20µs, as long as you are not facing load dump or a similar event, it is unnecessary to account for 10/1000µs.

    For TVS diode implementation, the primary criteria are as follows:

    • Working Voltage (determining what is the operating voltage on the line being protected, and ensuring selection of a diode that has a working voltage at/above this operating voltage)
    • Clamping Voltage (determining any downstream absolute maximum ratings, and choosing a clamping voltage at/below these ratings)
    • Surge Rating (determining any longer transients that may occur and choosing the expected current rating needed to protect against these)

    There are other specifications that may be critical for specific applications, such as package or leakage current, but the above 3 line items are the most critical for TVS diodes.

    Best Regards,

    Josh Prushing