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TLIN1027-Q1: Can we connect TLIN1027 to 24V pulled up K-Line when TLIN1027 Vsup is 12V ?

PYTsai
Genius 9805 points
Part Number: TLIN1027-Q1
Other Parts Discussed in Thread: TLIN2027-Q1, TLIN2029EVM

Hi 

Can we connect TLIN1027 to 24V pulled up K-Line when TLIN1027 Vsup is 12V ?

Thanks!

  • 0
    Guru 258450 points

    VLIN is allowed to be higher than VSUP. But note that the TLIN1027-Q1 itself pulls the line up to VLIN.

  • 0
    TI__Mastermind 24065 points

    PY,

    Keep in mind that the thresholds of high/low on LIN are determined based upon a percentage of VSUP. While the TLIN1027-Q1 will survive this condition, the lower VSUP = 12V will reduce the input LOW threshold of the TLIN1027-Q1 down to 0.4 * 12V = 4.8V instead of 0.4 * 24V = 9.6V.

    Best,

    Danny

  • 0 in reply to Danny Bacic
    Prodigy 20 points
    Sorry, update my questions.
    1. For TLIN1027, we will not use the LIN interface for our project but K-Line(ISO9141).
    So could I input the K-Line(ISO9141) signal to the Pin6 of TLIN1027 directly?
    2. And K-Line will be pulled up to Vbat(12V/24V), but TLIN1027 could support for 12V application.
    So does that still work for our application?
  • 0 in reply to Hampton Hsia
    TI__Mastermind 24065 points

    Hampton,

    No worries, please feel free to ask questions if they come up.

    The TLIN1027-Q1 and TLIN2027-Q1 are intended to be compatible with ISO 9141 applications since they do not have a dominant state time-out feature. This allows LIN to stay dominant indefinitely which may be needed for ISO 9141.

    TLIN1027-Q1 will still use VSUP as a reference for LIN input high/low thresholds. Regardless of VSUP, it will not be damaged for any LIN voltage level within the absolute maximum limit of ±45V for TLIN1027-Q1 and ±60V for TLIN2027-Q1, so it will survive a pull-up to 24V when VSUP = 12V.

    I bring up the input high/low thresholds to make sure you're aware that this could impact timing on TXD/RXD due to the threshold shifting lower. If this is okay for your MCU/controller, then it should be acceptable.

    Best,

    Danny

  • 0 in reply to Danny Bacic
    Prodigy 20 points

    Hi Danny,

    1. In out application, the MCU voltage domain is 3V3, and K-line may pull up to 12V or 24V(VSUP). Based on these information, could you address more about the high/low thresholds issue? Do you mean the higher pull up voltage would cause the duration of TXD/RXD transition higher?

    2. If we want to do the K-Line prototyping, do you think TLIN2029EVM is a appropriate EVM to start?

    Thanks,

    Hampton

  • 0 in reply to Hampton Hsia
    TI__Mastermind 24065 points

    Hampton,

    The TLIN1027-Q1 is reading/receiving from the LIN pin to pass the LIN bus state to RXD. The threshold for LIN high/low is determined as a percentage of VSUP. You just need to make sure that every output LOW voltage from any device on the bus is definitely lower than the lowest input low threshold for any device on the bus. This is not an issue when every device has the same VSUP, but if you give different devices different VSUP levels, you have to ensure that they're compatible. Otherwise the transceiver might not read the LIN bus correctly.

    Regarding EVM, yes, the TLIN2029EVM would be the best to evaluate the component.

    Best,

    Danny