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LM5069 Application Question

Kuo Nowal
Expert 2315 points
Other Parts Discussed in Thread: LM5069, CSD19536KTT

Hi sir,

My customer currently survey  surge protector application Ethernet Switch Vin 54V, test condition is 2kV common mode 2 ohm / Differential mode 12 ohm

May I know LM5069 can suitable this case? if not, could you advise better solution? thanks.

  • 0
    TI__Genius 10370 points

    Hi Kuo, 

    How is your lightning surge connected to the LM5069 (or your system) in both the differential mode and the common mode. Attaching schematics would be helpful. 

    For a 2kV / 12ohm (166.7A) test, the LM5069 in addition to connecting TVS diodes from VIN to GND can protect against a lightning surge. Make sure the TVS diode has a reverse stand off voltage above 54V,  a max clamping voltage of under 100V (absolute max of the LM5069), and that it can withstand 167A of current at the Vmax voltage. For this to be achievable, you might have to put several TVS diodes in parallel. Having three TVS diodes in parallel, like the Littlefuse 5.0SMDJ58A, would probably work.  Look at picture below for a TVS Diode connection:

    Best Regards,

    Aramis P. Alvarez

  • 0 in reply to Aramis P. Alvarez
    Expert 2315 points
    Hi sir,

    Thanks for your reply.
    Could you help suggest HOTSWAP MOSFET for 2kV/2ohm (current MAX up to 1000A) test ?
  • 0 in reply to Kuo Nowal
    TI__Genius 10370 points

    Hi Kuo,

    For 1000A, you would probably need many TVS diodes in parallel. As stated above, if you have a schematic on how you're connecting the surge test that would be very helpful. The MOSFET chosen should be at a Vds rating equal to 100V (the same value as the LM5069 absolute max for VIN). A strong SOA FET, such as the CSD19536KTT, will offer the best protection. I hope this helps :-)

    Best Regards, 

    Aramis P. Alvarez

  • 0 in reply to Aramis P. Alvarez
    TI__Genius 10370 points

    Hi Kuo,

    Another type of TVS Diode that would probably work would be the AK3-058C, which could clamp 3,000A @ 110V, but this is all dependent on how you have the test surge connected to both the differential and common mode.

    Best Regards,

    Aramis P. Alvarez