• State
  • Locked Locked
  • Replies 4 replies
  • Subscribers 33 subscribers
  • Views 217 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TLIN2029-Q1: Cannot find pullup load conditions for VOL spec In the datasheet

Reid Adriance
Prodigy 20 points
Part Number: TLIN2029-Q1

In the datasheet, I cannot find a load value for the VOL spec in the LIN PIN section of the Electrical Characteristics table.  Is a 1k Master Node pullup assumed?  Or 500 ohms?  For VSUP = 12V, the datasheet gives VOL of 2.4V maximum, which seems quite high unless there is some significant pullup loading.  Thanks for help with this.

  • 0
    TI__Guru 62910 points

    Hi Reid,

    Our team is currently out of the office due to the US holiday, but we will get back to you later this week.

    Regards,
    Max

  • 0 in reply to Miguel Robertson
    TI__Guru 62910 points

    Hi Reid,

    Sorry to keep you waiting on this.  I confirmed with the team, though, and it seems that for this spec the test load was just the internal pull-up resistance of the device.  Measured data is significantly lower than this spec limit, though, since the pull-down driver is reasonably strong and there is very little sink current with just the internal resistance (~45 kOhm).

    To give a little bit better point of reference, when we pursued compliance testing the VOL of the device was evaluated using a standard SAE J2602 slave node pull-up load condition of 875 Ohms and the VOL was measured to be 0.786 V at a supply level of 18 V.

    Max

  • 0 in reply to Miguel Robertson
    Prodigy 20 points

    Thanks, Max.  The information is actually quite helpful. 

    I assume the result was at room temperature? 

    If so, we can estimate temp effects for our boundary conditions, but any other data you could share, especially at other ambient temperatures, would be helpful for our worst-case analyses.  We have some potentially long wire runs with relatively high return side voltage drops.  Margin for the low input voltage threshold at the master was getting very thin when blindly applying the datasheet limits for VOL at the downstream slave.  

    Will there be a datasheet update to clarify any of this?

    Thanks again!

  • 0 in reply to Reid Adriance
    TI__Guru 62910 points

    Hi Reid,

    I've been discussing this with our design team for a little bit since I realize it is hard to extrapolate out our VOL specification to different loading conditions.  They confirmed that although it is not specified this way in the datasheet, the device is capable of driving the specified VOL level even with a 500-Ohm pull-up resistance across the full recommended VSUP and operating temperature range.  Hopefully that info will help buy you some margin, since it indicates a much stronger pull-down driver than assuming VOL is met only with a 45 kOhm load.

    Max