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TPS26630-33EVM: Increasing surge/eft level compliance

Colin Fraser
Prodigy 145 points
Part Number: TPS26630-33EVM
Other Parts Discussed in Thread: TPS2663

The evaluation board is rated for surge protection up to 500V (IEC610000-4-5 Level 1). I was hoping to modify it to handle up to 4kV (IEC610000-4-5 Level 4).

I have an operating voltage of 24V and a current up to 500mA. I tweaked the UVP and OVP setpoints and that seems okay.

But for modifying the surge protection level I tried removing the TVS and using the MOV V10E20P which has a current surge rating of 2kA which I need. However, when I tried running a surge test at +1.5kV it looks like the TPS2663 died on me and now all of the pins on it are shorting together. The clamping voltage of the V10E20P is 65V, is that a little too close to comfort for the maximum IN_SYS rating on the TPS2663 of 67V? Are there any recommendations on how to modify the front of the circuit to handle a surge of this size? The combination of EFT, overcurrent protection and reverse polarity protection are why I'm interested in the efuse.

Thanks,

Colin

  • 0
    TI__Guru** 105361 points

    Hi Colin,

    Thanks for reaching out!

    How much transient voltage you measured on board between IN_SYS and GND pins of TPS2663 device ? 

    Is it still ~65V as per your MOV clamping voltage ?

    Best Regards, Rakesh

  • 0 in reply to Rakesh
    Prodigy 145 points

    Hi Rakesh,

    I had been kind of nervous to actually hook up the oscilloscope and measure the surge. But I ended up seeing how the MOV did even with a surge as little as 250V and it did (for ~20us) shoot up to more like 75V. So it seems like I'm going to need much more room between the listed clamping voltage and max rating.

    Cheers,

    Colin

  • 0 in reply to Colin Fraser
    TI__Guru** 105361 points

    Hi Colin,

    The dynamic impedance of the clamping devices play key role here. I think, surge currents of such level should be managed by multi-stage filter... MOV, LC filter and then followed by TVS diode close to the IC. We usually see 500V type of surge support requirement and unfortunately don't have much to suggest on the guidelines for LC filter design. Please explore there could be several literature available.

    Best Regards, Rakesh