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Original question:

TCA9546APWR

TCA9546A: SCH review

Leo Chung
Prodigy 30 points
Part Number: TCA9546A


can you help review TCA9546 SCH for us?M305_CENTURY-0803-V100-1006_SMBUS.pdf

  • 0 in reply to Leo Chung
    TI__Guru 54238 points

    Hi Leo,

    The schematic looks good. What is the lowest pull-up voltage in the system? It looks like 3.3V is the main pull-up voltage. Are there any 1.8V rails? 

    Are there pull up resistors on pins 4,5, 9,10, and 11,12? I am wanting to make sure that there are pull-up resistors on each channel. 

    Pull up resistors present on the PCIE side? 

    Everything else for the schematic portion looks good. 

    For the layout, I didn't see any major flaws. Looks like there are large ground and VCC planes which is good for larger current flows. For the I2C bus channels, I see that the traces are fairly long and exist across most of the card. Please keep in mind that for every inch of PCB trace acquires about 3pF of capacitance. Longer traces = more capacitance = slower rise-times. The inductance added also might create spikes on the falling edge of the I2C waveform. IF this becomes a major problem in application, consider adding series resistance to mitigate the spike. 

    Regards,

    Tyler