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Original question:

SN74AVC4T774: 3V3 to 1V8 Level shifter/Voltage translation device to support SPI

SN74AVC4T774: cascade SN74AVC4T774 for SPI application

Hector Chen
Intellectual 370 points
Part Number: SN74AVC4T774

Tool/software:

Hi Sir,

SPI clock rate around 5MHz

Do you recommend SN74AVC4T774 for the SPI application below?

What should we pay attention to in the application? for example, load capacitance

Do you have any requirements on the input signal of the level shifter? for example, rise time, fall time, etc. 

Thanks

Hector

  • 0
    TI__Genius 13540 points

    Hello Hector,

    Yes, I would recommend the AVC4T774 for SPI applications. Since it is SPI, I would pay attention to the distance between the master and slave since this will increase your propagation delay. 5MHz is typical for SPI but if you happen to have a long trace/cable length, you may experience missing bits.

    For input requirements, I would follow the recommended conditions found in the datasheet.

    Regards,

    Josh

  • 0 in reply to Joshua Salinas
    Intellectual 370 points

    Hi Josh,

    Do you have examples showing missing bits when using long trace/cable length?

    We will use a 130mm coaxial cable to connect main board and sensor board.

    Thanks.

    Hector

  • 0 in reply to Hector Chen
    TI__Genius 13540 points

    Hello Hector,

    This reference design (TIDUED8) notes talks somewhat about the effects of prop delay on SPI clock and how LVDS could be used to resolve it. However, this mainly applies to cable lengths >1m.

    I don't see an issue with using a 130mm coaxial cable to connect main and sensor board.

    Regards,

    Josh

  • 0 in reply to Joshua Salinas
    Intellectual 370 points

    Hi Josh,

    Update the topology and list the number of slaves connected to the bus.

    Do you have any concerns?

     

    Thanks 

    Hector

  • 0 in reply to Hector Chen
    TI__Genius 13540 points

    Hello Hector,

    I don't see any issues with the updated topology. Thanks.

    Regards,

    Josh