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TPS54335A: Current limit for Low side FET.

Kengo.Y
Guru 11245 points
Part Number: TPS54335A

Tool/software:

Hi team,

According to the data sheet, Low-side switch sinking current-limit is 0A typ.
Does this mean that it cannot be less than 0A?



If you have MIN spec, please let me know.

BR,
Kengo.

  • 0
    TI__Mastermind 27286 points

    Hi Kengo

    The TPS54335A enters into DCM  and pulse skipping mode under light load.  That means the LS will shut down when iL reaches 0. （relevantly there is FPWM mode that always operate under CCM mode even under no load）.

    This feature can help achieve high light load efficiency.

    Sorry that there is no min value specified. 

    Thanks and best regards.

  • 0 in reply to Gui He
    Guru 11245 points

    Hi Gui,

    Thank you for your reply.

    LS current limit is in Absolute Maximum Ratings.
    Does this mean that the IC will break if this current limit is exceeded?



    BR,
    Kengo.

  • 0 in reply to Kengo.Y
    TI__Mastermind 27286 points

    Hi Kengo

    The device has peak current limit protection for both HS and LS.  You can refer to 7.3.13 Overcurrent Protection for more details:

    We recommend select inductor with current rate > the high side swich current limit for secure operation.

    Thanks

  • 0 in reply to Gui He
    Guru 11245 points

    Hi Gui,

    My understanding is that the data sheet wrote in Absolute Maximum Ratings but it's not broke when current exceeded.
    Is it right?

    BR,
    Kengo.

  • +1 in reply to Kengo.Y
    TI__Mastermind 27286 points

    Hi Kengo

    The device is designed to operate with current < the absolute maximum ratings, this current limit shouldn't be exceeded. And there is cycle-by-cycle current protection in the device, HS will shut down when iL hit the current limit and stop iL from rising up. Normally the limit will not be exceeded. 

     

    Under special conditions like the inductor is saturated and the inductance is very small, the iL rising slew rate is very fast and the iL might exceed the limit value , this might cause risk, so we recommend select inductor with current rate > the high side swich current limit for secure operation.

    Thanks and best regards.