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TPS24750: May we know how to set up TPS24750 current in 5A?

Chen Bogey8
Mastermind 9990 points
Part Number: TPS24750
Other Parts Discussed in Thread: TPS25940

Hi Sir 

My customer application TPS24750 in 17V and current limit want set in 5A, but i am not sure which formula can be use? and how to know the accuracy?

                                                                              Bogey

  • 0
    TI__Guru** 105361 points

    Hi Bogey,

    Thanks for reaching out.

    what is the application use case, max input voltage and max load current?. If it is around 5A, I would recommend to look at TPS25940 device.

    For TPS24750, the offset variation across the sense resistor determines the current limit accuracy, which is around +/- 10%

    Please use the design calculator at http://www.ti.com/product/TPS24750/toolssoftware  and application example given in the datasheet. 

    Let me know if you face any challenge in using the design calculator.

    Best Regards

    Rakesh

  • 0 in reply to Rakesh
    Mastermind 9990 points

    Hi Rakesh

    Use in 17V application. Because customer want limit current at 5A. Is TPS24750 can use?

    If i set at 5A, may i know the tolance?

                                                                         Bogey

  • 0 in reply to Chen Bogey8
    TI__Guru** 105361 points
    Hi Bogey,

    TPS24750 can be used for over current protection at 5A. For 5A, the tolerance of current trip is +/- 10% + variation in sense resistance. If a 1% sense resistor is chosen, then it will be +/- 11%. The min and max current trips are 4.45A and 5.55A

    Please note TPS24750 is a circuit breaker device. when the overload current exceeds the set current limit 5A (typ), the device does not limit output current to 5A(typ) but provides overload current for brief fault timer period programmed at TIMER pin.

    Regards
    Rakesh
  • 0 in reply to Rakesh
    Mastermind 9990 points

    Hi Sir

    Is it mean if i set over current is 5A, but i force load to 6A, the 6A will alos folw to LOAD. The TPS24750 just sent fault signal to control side. am i right?

    unless customer have other circuit ti limit the current. Am my undersanding is right?

    If yes, may you have advise 17Vin over current limit set in 5A auto retry solution to us?

                                                                Bogey

  • 0 in reply to Chen Bogey8
    TI__Guru** 105361 points
    Hi Bogey,

    yes, 6A will also flow to the load for fault period tFLT. The fault signal gets asserted only after tFLT time.
    Please refer Figure 33 and section 9.4.4 for details on over current response of TPS24750.

    I recommend to consider TPS25940A device and set 5.2A (typ) current limit. It has +/- 8% current limit accuracy and for over load current, the device limits load current between 4.78A and 5.62A. TPS25940A is auto retry solution.

    Regards
    Rakesh
  • 0 in reply to Rakesh
    Mastermind 9990 points
    Hi Sir
    thanks for you reply, so if we use TPS25940 in our application, even we load reach 6A.
    The TPS25940 still limit current at 4.78A~5.62A, right? or TPS25940 will go to protection mode that direct latch(or auto retry).
    Bogey
  • 0 in reply to Chen Bogey8
    TI__Guru** 105361 points
    Hi Bogey,

    TPS25940 will limit current between 4.78A~5.62A, if your load reaches 6A. Then the device goes into latch/auto-retry mode based on the device version.
    The maximum load current that TPS25940 can serve without current limit is 4.78A.

    Rakesh