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TCAN1042V-Q1: TCAN1042VDRQ1 RC Network Applications Concerns?

Ken Chen39
Intellectual 545 points
Part Number: TCAN1042V-Q1

Hi TI Team，

Questions about the choice of R and C values in the application of Split Termination mode of TCAN1042VDRQ1 chip:

The selection range of the resistance value of R. In some application scenarios, the resistance value is chosen as 1.3K instead of 60Ω. What is the reason?

What is the capacity of C?

  • 0
    TI__Guru 74252 points

    Ken,

    The value of the termination resistance depends on the bus topology used and where in that topology the particular node is located. In general, you want the end nodes to have 120 ohms of termination total (two 60 ohms in series for split termination) so that every node on the bus will see 60 ohms overall bus impedance (2x 120 ohms in parallel). When a high valued termination resistance is seen, this is typically for mid-nodes that still need to have some damping of the signal so the signal is absorbed and reflections are mitigated. You also want to keep this high-valued so that it does not decrease the overall bus impedance value too greatly. The overall bus impedance should stay between 50 and 60 ohms, preferably closer to 60 ohms.

    The range for the split capacitor is 4.7nF to 100nF. Most often I see customers using 4.7nF, though it will depend on the RC constant you need based on your datarate.

    Regards,

    Eric Hackett