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TPS22919: Soft Start function

user1557649
Prodigy 60 points
Part Number: TPS22919

I would like to prevent inrush current from capactor on other board when I link the cable with the board.

I'm worried about bouncing due to hot-swap.
　① Can the soft start function of TPS22919 be used every bouncing ?
　② Would it be possibel to tell me the operating principle and internal structure of soft start about TPS22919?

Best Regard,

  • 0
    TI__Mastermind 32650 points

    Hi User,

    1. Soft start is used whenever the device turns on. Thus the device has to be disabled and then enabled again for soft start to take place.

    2. Please refer to Chapter 2 on this white paper for some more details on soft start: https://www.ti.com/lit/wp/slyy168/slyy168.pdf 

  • 0 in reply to Shreyas Dmello
    Prodigy 60 points

    Hi, Shreyas Dmello-san,

    Thank you for your prompt reply. I checked your answer and I have additional questions below;

    >1. Soft start is used whenever the device turns on. Thus the device has to be disabled and then enabled again for soft start to take place.

    -> "The device has to be disabled" means that once the softstart is effective, unless Vin get to be lower than 1.6V again, the softstart function remain to be disable. Is my understanding correct?

    >2. Please refer to Chapter 2 on this white paper for some more details on soft start:

    -> I checked Chapter 2. I think this chapter explain mainly three cases. In the case of TPS22919, which feature does TPS22919 have, "TC time constant"  or  "Linear soft-start or dV/dt" or other ?

    Best Regards,

    Toru

  • 0 in reply to user1557649
    TI__Mastermind 32650 points

    Hi Toru,

    1. No, by disabled I am referring to the ON pin being pulled low to turn off the device and then pulling ON high to turn on the device. The device does not have to lose power.

    2. All our load switches have "linear soft-start or dv/dt"

  • 0 in reply to Shreyas Dmello
    Prodigy 60 points

    Hi, Shreyas Dmello-san,

    Thank you for your quick response , again.

    I'm sorry many times, but I have more questions. At this time, we have the ON pin connected to Vin. This Vin is used by connecting it to the 2.5V of the LDO of another device via a cable. Therefore, I thought that if Vin falls below 1.6V, it will be disabled before the ON pin(because Vil of the ON pin is 0.35V.). I thought that if either Vin or the ON pin falls below each  VIL, it will be disabled. Is that correct?

    Best Regards,

    Toru

  • 0 in reply to user1557649
    TI__Mastermind 32650 points

    Hi Toru,

    Yes. If you have VIN and ON tied together, the device will turn off and be unpowered at 1.6V.

    Every time the input rail rises over 1.6V, soft start will be used.

    Thank you for choosing TI Power Switches