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UCC256402: Risns resistor

ali aykan
Prodigy 130 points
Part Number: UCC256402

Hi,

1. How can I calculate the Risns power rating? Webench power designer shows 0W according to input parameters. 

2. Webench power designer schematic is broken as in attachment fo a while. 

  • +1
    TI__Genius 16155 points

    Hi Ali,

    Thanks for reaching out to us.

    You can use the design calculator (https://www.ti.com/lit/zip/sluc675 ) incase webench is still not accessible.

    For Risns, you can use 0.1W 0603 footprint.

    For power rating calculation, please see the ISNS pin differentiator section of the data sheet (page 58).

    Here OCP3 value is 0.43V which is average value of the input current (which is measured when upper switch is turned on).

    Here VISNS average value is 0.331V assuming 130% over load.

    So, worst case power rating would be 0.3312/132 = 83mW.

    Please let me know if you have any further questions.

    Regards

    Manikanta P