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TPS2372: Classification Resistor Tolerance

Part Number: TPS2372

Hello,

Class 8 PD specifies a 63.4 ohm resistor. Can a 64.9 ohm resistor be used instead? Or will that cause problems?

Thanks,

Michael

  • Hey Michael, 

    Yes a 64.9ohm resistor should be okay. The IC will place 2.5V across the resistor when there is a class finger. The current needs to be between 36mA and 44mA for a Class 4 signature. Note for IEEE802.3.bt standard, class 8 is technically a class 4 signature and a class 3 signature. 

    For V/R =I >>> 2.5V / 64.9ohm = 38.5mA, so I think we should be good. 

    Just note that the class current is 38.5mA, so typically this resistor is 0805 or larger size. Can't do a 0402 Slight smile

    If this post answers your question, please indicate so by marking this thread as resolved. Thank you.

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments