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TPD3S716-Q1: Current limit accuracy

Part Number: TPD3S716-Q1
Other Parts Discussed in Thread: TPS2549-Q1

Hi,

We got a question from the customer about TPD3S716-Q1.
Could you help us?

[Question]
They need to improve current limit accuracy. They require current limit is greater than 2.5A and less than 2.9A. If they use more high accuracy resistor, not 1%, does the IC meet their requirement?

Best Regards,
tateo

  • Tateo,

    A more precise resistor will improve the current limit accuracy; however, the range is set by a non-linear function, so I will have to do some research before I can answer your question. The datasheet calculators are based on a 1% resistor and will have to be modified for 0.1% accuracy

    I will follow up with you on Tuesday next week as I will not be in the office on Monday.

    Regards,
    Chuck
  • Hi, Thank you for your quick reply. I look forward to your feed back.

    Best Regards,

    tateo

  • Tateo,

    Unfortunately, making the resistor more accurate will not result in the range that the customer has requested.  

    I did some calculations using the datasheet calculator and some variation in the 56.7k R value.  The calculations show that system parameters other than the R value prevent the more accurate resistor from  meeting the specification.

    R R-.1% R+.1%
    Datasheet 
    R 57.6 57.5424 57.6576
    ILNOM 2.65975 2.662367 2.657138
    ILMIN 2.398885 2.40126 2.396515
    ILMAX 2.880695 2.883455 2.877941
    Meet 2.5A Min
    R 55.2 55.1448 55.2552
    ILNOM 2.773383 2.776112 2.77066
    ILMIN 2.502014 2.50449 2.499542
    ILMAX 3.000459 3.003333 2.997589
    Meet 2.9A Max
    R 57.2 57.1428 57.2572
    ILNOM 2.678032 2.680667 2.675402
    ILMIN 2.415478 2.41787 2.413091
    ILMAX 2.899971 2.902749 2.897198

    If there is anything else I can do do help, please update this thread.  If this answers your question, then please reply back. If your question is answered, please click  Verify Answer 

  • Hi, Thank you for your support. We got additional question.

    - Can the IC disable the current limit function?
    - Or how much is the recommended Rlim value which minimum current limit is grater than 2.9A?

    They are considering a below block diagram. They will use current limit(2.5 to 2.9A) by TPS2549-Q1. So they want to disable current limit of the IC.

    Best Regards,
    tateo

  • Tateo,

    The closest way to disable the current limit function is to use a 30kohm resistor for RADJ. This will cause the current limit circuit to essentially stop limiting current. The calculated current limit is 5A, but will be less than this in practice

    Please let me know if I can help any further.

    Regards,
    Chuck
  • Hi, Sorry for the delayed reply. Thank for your support. Your support is very helpful. So we got additional question. Could you confirm it?

    In their following condition, there is possible that 2.5A current flows through the IC.

    Vout=5.5V
    Iout=DC2.5A
    Ta=25C or 70C

    - If Tj doesn't exceed maximum rating, can the IC survive without reducing reliability? They understand we should also care electromigration. And they want to know wheter the IC has capability to survive in their condition, or not.
    - If 2.5A current through the IC in their condition, are there any possibility to occur smoking or firing?

    They understand it is out of the maximum rating and possible to damage the IC. But they want to make sure the capability of the IC.

    Best Regards,
    tateo