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Using Load Switch to HotSwap application

K. Sasaki14
Guru 10200 points
Other Parts Discussed in Thread: TPS22924C, TPS22924

Can we use Load SW device (TPS22924C etc...) to HotSwap application?
The application is optical module.
Our customer don't place the input capacitor for load switch device.

In this condition can we use load switch? or should we use efuse device?
If load switch is not fit for hotswap requirement, please let me know the reason.

Best Regards,
Kohei Sasaki

  • 0
    TI__Genius 15780 points

    Hi Kohei,

    Our load switches are not typically used for hot swap applications due to the lack of protection features.  Any over voltage or over current events would risk damaging the load switch due to no OVP or OCP features.  Our eFuses, on the other hand, have these features and are typically used for hot swap applications.

    However, we have seen our TPS22925C (upgrade to the TPS22924C) used in optical modules for inrush current control at the input.  Is this for a 3.3V input?  If so, what sort of voltage/current transients are expected on the input of the TPS22924/5?

    Thanks,

    Alek Kaknevicius

  • 0 in reply to Aleksandras_Kaknevicius
    Guru 10200 points
    Alek-san,

    Thank you for your answer.
    The input voltage is 3.3V. Sorry, I don't have data of voltage and current transient now.
    Do you have any guideline of voltage and current transient level for using TPS22924/5?


    Best Rgards,
    Kohei Sasaki
  • 0 in reply to K. Sasaki14
    TI__Genius 15780 points

    Hi Kohei,

    The maximum voltage rating on the TPS22924/5 is 4V and the max current which can be put through the device for 100us is 4A.  Let me know if you have any additional concerns or questions.

    Thanks,

    Alek Kaknevicius

  • 0 in reply to Aleksandras_Kaknevicius
    Guru 10200 points

    Alek-san,

    Our customer's concern is input capacitor.
    They would like to remove the input capacitor as much as possible.
    1uF ceramic capacitor is recommended for TPS22924C input capacitor. I think that output capacitor of DCDC in front of TPS22924 makes up for Cin capacitance for CL. Is this my  idea correct?

    Customer's evaluation is of course necessary. 

    Best Regards,
    Kohei Sasaki

  • 0 in reply to K. Sasaki14
    TI__Genius 15780 points

    Hi Kohei,

    While the 1uF is recommended, it is not necessary.  This capacitance is more for the power supply to handle the transients caused by the load, not for the load switch to operate.  Also, you are correct, the output capacitor for the DC/DC will provide some of this capacitance for the load switch.

    Thanks,

    Alek Kaknevicius