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TLIN1029-Q1: Specification of VOH and VBUSrec

Michiaki Tanii
Expert 4610 points
Part Number: TLIN1029-Q1

Hi

Could you kindly advise the below ?

1. Why are there large difference of output voltage for VOH and VOL of LIN bus between less than 7V and more than 7V ?

2. In the case of Vsup = 5V (±5%) connecting driver with receiver, according the datasheet, VBUSrec is described min 0.6Vsup against VOH min 3V.
Considering variation of Vsup = 5V (±5%), might the connection be failed ?

In my understanding, VOH is determined by external pullup resister, internal pullup resister and Rds_on of internal FET so I don’t think the phenomenon of 2. would not be seen.

Please kindly advise why VOH, VOL and VBUSrec is specified like datasheet.

Thank you and best regards,
Michiaki

  • 0
    TI__Mastermind 33050 points

    Hello Michiaki,

    You are correct in your understanding that the VOH is determined by an external pullup resistor and most applications use a VSUP of greater than 7V (i.e. 12V or 14V for automotive applications).  In order to meet the duty cycle requirements, a certain amount of current is needed to meet the rise time in this architecture.  At low VSUP voltages, there isn't enough current with just the pullup resistor and the TLIN1029 device has an extra circuit that helps inject current to accelerate the rise time and duty cycle requirements. This is why there is a difference in the datasheet spec for VSUP > 7V, and VSUP < 7V.

    I also agree with you in that your second question is not probably a situation that is likely.  The specifications are most likely have some overlap in the extreme worst case overlap due to some additional guard band on the numbers to ensure a device would never fail the spec.  However, since this is based on a pullup resistor to VSUP, I would find your scenario unlikely.  But thank you for bringing this to our attention.

    I hope this answers your questions, if not please let us know.

    Regards,

    Jonathan