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TMP464: trace between transistor and TMP464

Toshihiro Watanabe
Genius 10235 points
Part Number: TMP464

Hello,

There is a layout example in figure 24 of datasheet. I would like to ask about D- connection point.

The distance between transistors and TMP464 is around 10cm. We would like to connect 4 cathode connection point around the D- pin.

If we do so, is it affect the measurement accuracy?

If no issue, is it ok to follow figure 23, pair D+ and D- and guard by GND and V+?

Best regards,

Toshihiro Watanabe

  • 0
    TI__Mastermind 22430 points
    Hi Toshihiro-San,

    When you say you want to have cathode connection points around the D- pin, will these be for attaching remote transistors for temperature measurement? Or are they for another purpose?

    Traces of around 10cm in length shouldn't be an issue for the TMP464 provided not too much noise is being conducted. You should definitely shield the traces as shown in figure 23 to help with this.

    Best Regards,
    Brandon Fisher
  • 0 in reply to Brandon Fisher94
    TI__Genius 10235 points
    Hello Brandon-san,
    Use transistor for remote temperature purpose. There is a restriction we want to connect 4 cathode trace around D-pin. In this case, Anode and cathode trace are routed between transistor and TMP464. Is it ok the pair is side by side like LVDS trace and connect cathode side around D- pin? I think it is not too restrictions so it would be ok though.
    Best regards,
    Toshihiro Watanabe
  • 0 in reply to Toshihiro Watanabe
    TI__Mastermind 22430 points
    Hello Toshihiro-san,

    It's difficult to say if this would cause an issue. Diode traces for remote temperature sensors are particularly sensitive to noise, as the voltages being read back to the sensor can be extremely small.

    Whether or not this would be a problem will depend on what kind of signals are on the nearby traces. If there is a lot of switching on these traces then you could expect to see at least some crosstalk, which may prevent reading of the remote diodes.

    Best Regards,
    Brandon Fisher