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TUSB2046B: Termination Resistance

Jacopo Agostini
Intellectual 390 points
Part Number: TUSB2046B


Hi, from TUSB2046B datasheet is said that the proper series resistor on each USB line to ensure proper termination is 27 ohm. The correct USB termination differential resistance is 90 ohm, so I can assume that inside the device there are some resistances that combined with 27 ohm give the requested 90 ohm differential termination. Is it correct?

  • 0
    TI__Mastermind 18655 points
    Hello Jacopo,

    That is correct. Per USB 2.0 specification, the differential impedance must be 90-Ω differential or 45-Ω single-ended. Having series resistors between 22 Ω to 33 Ω along with internal resistance of the device ensures that the impedance matches this specification.

    Regards