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TXS0102-Q1: DESIGN REVIEW

Melbin Manuel
Intellectual 300 points
Part Number: TXS0102-Q1
Other Parts Discussed in Thread: SN74LVC1T45-Q1, SN74LVC1G125-Q1

Hello,

Kindly review the attached design using TXS0102QDCURQ1
Thanks,

Melbin

TXS0102QDCURQ1_SCH_28DEC2020.pdf

  • 0
    Prodigy 180 points

    Hello,

    We are working on a project with TXS0102QDCURQ1 in it.
    Kindly review the attached schematics and let me know the review comments.

    TXS0102QDCURQ1_SCH_28DEC2020.pdf

  • 0
    TI__Guru* 96681 points

    Hi Melbin,

    The TXS0102-Q1 has internal 10-kΩ pull-up resistors on all I/O ports (Ax and Bx), so the external resistors R2 (D), R4, R2630 (D), and R2639 can interfere with the operation of the device. For example, R4 being a 20k pull-down will cause a voltage divider with the 10k internal pull-up resistor and the node will be forced to about 3.3V. I realize that 'D' most likely indicates a non-populated resistor, but I want to mention this to avoid confusion since they may be used later.

    It looks like the outputs are remaining active at all times, so the pull-up resistors R2637, R2638, R2640, R2641, and R2642 are not required. The OE pins can be directly connected to VCCA.

    Otherwise the schematic looks good. I can't see the load, on either A or B port, so please take note that this device is very sensitive to heavy loads. You should maintain under 70pF at all I/O pins, and avoid long traces. Either of these can result in oscillations.

  • 0
    Guru 257450 points

    The TXS has internal pull-up resistors; the pull-down on the MPS signal will not work. I'd suggest the SN74LVC1T45-Q1 for this.

    U357 looks OK (if the signals can handle the pull-up resistors), but what is the purpose of U356/U358/U359, where both voltages are the same? Do you want some kind of isolation when one power supply is off? Or might the CAN voltage change later?

  • 0 in reply to Clemens Ladisch
    Intellectual 300 points

    For U356/U358/U359 the purpose is to provide isolation between both section. 

    Here one power may be present when the other is not present, So in order to avoid a leakage path, we implemented this logic.

  • 0 in reply to Melbin Manuel
    Guru 257450 points

    You do not need level translators to prevent leakage. It is enough to use a plain buffer with overvoltage-tolerant inputs and/or Ioff, e.g., SN74LVC1G125-Q1.

  • 0
    TI__Mastermind 24045 points

    Melbin,

    I noticed that you have already posted this. In an effort to consolidate posts on E2E, I have merged the threads.

    Best,

    Danny