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TLIN1021A-Q1: wake up source recognition

Akihiro Hirata
Expert 6320 points

Part Number: TLIN1021A-Q1

Hello team,

TLIN1021A-Q1 has the function which can let us know which wake source get the LIN to wake.

The weak pull down is 350kOhm shown below, and hard pull-down shown below as FET respectively correct?

And these characteristics are shown below, right?

Question

1. Hard pull down characteristics is specified as ITXD(WAKE) in case TXD=1V. 

    Does this mean the pull down resistance in case local wake is the wake up source is from 125Ohm(=1V/8mA) to 769Ohm (=1V/1.3mA)? 

2. When we would like to recognize wake up feature what circuit is recommended?

   Pull up the TXD with approx. 10kOhm resistor or something like this?

Thanks.

Regards,

Hirata

  • +1
    TI__Guru 53535 points

    Hi Hirata-san,

    Yes, the characteristics here are related to the pull-down function on the TXD pin for wake source recognition. 

    1. Exactly correct here. The sinking current at a set voltage is an indirect way of measuring the pull-down resistance. Keep in mind that these specifications are across operating conditions, here likely mostly temperature dependant. This is why the range of values seems quite large. 

    2. Yes, a resistor network here would be a valid way of detecting which pull-down strength is being used by the transceiver. A 10k-ohm resistor for example would show a high-level (LIN bus wake up) with a voltage of 90%+ the pull-up reference (this will also depend on the MCU pin leakage). The low-level (WAKE pin wake up) voltage in this example would be <10% of the pull-up reference (again dependant on MCU leakage). The MCU will be able to sample this signal digitally to determine the wake up source.

    Let me know if you have any more questions.

    Regards,
    Eric Schott

  • 0 in reply to Eric Schott1
    TI__Expert 6320 points

    Hi Eric-san,

    Thanks so much for your speedy answer.

    I understood.

    I appreciate your support.

    Regards,

    Hirata