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Original question:

TLIN1029-Q1: 220pF at LIN pin in simplified schematics of datasheet

TLIN1029-Q1: External Capacitance at LIN Port

Shinichi Yokota
Genius 9715 points
Part Number: TLIN1029-Q1


Hello,

I'd like to ask a few questions relevant to this post about external capacitance at LIN port.

  • Is a 220-pF capacitor also recommended at a master node?
  • What's the purpose of this external capacitance in the first place?

Best regards,
Shinichi Yokota

  • 0
    TI__Guru 53575 points

    Hi Shinichi-san,

    Is a 220-pF capacitor also recommended at a master node?
    Yes, the only recommended external difference is the inclusion of the Master Node pull-up diode and resistor. 

    What's the purpose of this external capacitance in the first place?
    There are a few ways to answer this question, but I believe the easiest is to say that the LIN standard specifies a max of 250pF per node. Instead of individually keeping track of each node capacitance individually, many manufacturers choose to force each node to be near this specified max. The extra capacitance on the LIN bus is beneficial for factors such as slowing transient edges, and making it easy to keep track of total bus capacitance ensures that it doesn't rise high enough to slow signal edges.

    Let me know if you have any more questions.

    Regards,
    Eric Schott