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TLIN2029A-Q1: max low level voltage

Hanno Reimer
Intellectual 1610 points
Part Number: TLIN2029A-Q1

We have a question about TLIN2029A. The data sheet shows a max. Low-level voltage of 0.2 x Vsup. The specified range for Vsup is 4 to 48V. Therefore, we would have to expect a maximum low level of 9.6V at Vsup = 48V.

 However, our measurements with Vsup up to 35V show that the low. Level is never higher than 300mV. Our application requires that the low level does not exceed 500mV.

 Can it be that the specification in the data sheet is quite “generous”? Can we get a more precise indication? 

Thanks and bye 
Hanno 

  • 0
    TI__Genius 9895 points

    Hanno,

    The LIN physical layer specifies a dominant (low level) <= 0.4*VSUP. Our transceiver has specified 0.2*VSUP maximum so there's pretty much margin left. The maximum can be considered as the worst case. It doesn't necessarily mean the dominant voltage will be exactly 0.2*VSUP. As long as the voltage is below the max, there's no issue with it.

    I don't see any issue with 300mV dominant voltage at VSUP= 35V. It's also below your application's requirement of less than 500mV. 

    Regards,

    Sean

  • 0 in reply to Sean Guo
    Prodigy 10 points

    Hi Sean,

    I'm the customer who raised this question. I was hoping to get a confirmation, that the low level will never exceed 500mV. 

    We are targeting on solution which can connect to a LIN, but also to a non-LIN compliant device. This is the reason why staying below 500mV is important to us. 

    Is there a chance for taking a deeper look into the circuitry? We don't won't to rely on the measurement done with just one part.

    Thanks & Best Regards

    Horst

  • 0 in reply to Horst Theile
    TI__Genius 9895 points

    Hi Horst,

    Unfortunately, we cannot guarantee or confirm that the dominant voltage will never exceed 500mV, based on your VSUP= 35V condition.

    LIN is a single-ended communication scheme and the thresholds cannot be set by a voltage differential, these thresholds are based on a percentage of the battery voltage in the system. In order to achieve a 500mV max, the voltage supply needs under 2.5V, which is below the minimum recommended operating condition.

    Here is our characteristic data, from SIM and bench test. We haven't observed the low level voltage reaches or even close to 0.2*VSUP. 

    Regards,

    Sean