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TLIN1028-Q1: LIN-pin capacitor value

Atsushi Hirai
Expert 4950 points
Part Number: TLIN1028-Q1

Hi team,

My customer want to use 1000pF at leader node LIN-pin instead of 220pF to suppress an energy from some EMC test.

Is there any concern? Is there any point which they should evaluate?

Please give me your advice.

Regards,

  • +1
    TI__Guru 53555 points

    Hi Hirai-san,

    High bus capacitance on a LIN bus can increase the rise-time of a dominant to recessive transition. Too much capacitance could increase this time significantly enough to impact achievable data rates. However, LIN operates at relatively slow frequency so there is some margin to add extra. 

    LIN nodes typically include 220pF capacitors at each node, and the LIN specification limits the maximum number of nodes in a system to 16 (1 commander, 15 followers). This would make the total externally added capacitance in a LIN compliant bus around 3500pF. From this, we can say that a two or three node system with 1000pF capacitors at each node will still remain within normal operating conditions. Any larger system may choose to use smaller capacitor values to remain in this range. If the range is exceeded, it is possible that other changes such as a lower data rate may need to be considered to accommodate for the increased capacitive load. 

    Let me know if you have any more questions.

    Regards,
    Eric Schott