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SN65DP141 path impedance

Shu-Cheng LIN
Guru 11785 points
Other Parts Discussed in Thread: SN65DP141

Hi Sirs,

Sorry to bother you.

As Title, we need check SN65DP141 path  impedance.

Because we saw datasheet page 24

" NOTE: ALL DIFF PAIRS ARE ROUTEDTO 90 OHMS DIFFERENTIAL AND 50 OHMS COMMON MODE. ALL OTHER TRACES ARE 50 OHM "

From datasheet page 3 pin function DESCRIPTION

" Differential input, lane 0 (with 50 Ω termination to input common mode) "

It's confuse us between 50  Ω and 90  Ω.

Could you help explain it??

Thanks for your reply.

  • 0
    TI__Mastermind 23815 points

    Hi Shu-Cheng,

    90ohms is differential impedance, this is the impedance in the routing(PCB trace) of differential pairs, there is 90ohms impedance between positive and negative signal.

    The impedance is determined by several factors, trace width, high, separation, dielectric constant, which results in inductors and capacitors.

    50ohms resistance is the termination resistance to a bias voltage, you can see them in section 8.2 functional block diagram.

    Regards