SN74CBTLV3245A: Using as a Switch for SPI bootflash of Ultrascale Plus FPGA

Part Number: SN74CBTLV3245A
Other Parts Discussed in Thread: TMUX1511

Hi,

We have finalized SN74CBTLV3245APWR for using it as switch between Ultrascale Plus FPGA and SPI bootflash.

SPI bootflash supports max clock frequency of 166MHz.

But, we are using this SPI flash clock at 127.5Mhz which will be coming from FPGA.

This flash supports DDR also so the data rate will be 255MHz.

So my question is can we use SN74CBTLV3245APWR for 255MHz data rate?

Thanks,

Lalit

  • Hi Lalit,

    Thanks for your inquiry. We have one of our applications engineers looking into this and needs some time to look into this use case.

    Will reply back shortly!

    Thank you!

    Bryan

  • Hi Lalit,

    This is possible - but it depends on a few things and I'd like to ask a few clarification questions:

    1. What are the signal levels for SPI  that are being used in this application?


    2. What supply do you plan on using to power the mux?


    3.  Do you know what SPI bootloader you are using and which FPGA you are using - as the impedance at the pins of these connections can degrade bandwidth - especially parasitic capacitances from the FPGA/Bootloader.

    The multiplexer will act as a low pass filter - its cutoff frequency is dependent on the on resistance of the mux, the on capacitance of the mux, and the load impedance.

    Please let me know so I can verify if the part you are using has enough bandwidth.

    However with that being said - if the bandwidth is a bit short the TMUX1511 is only 4 channels (so 2 would be needed for 8 channels) and would have more than enough bandwidth to support the application. 

    Best,

    Parker Dodson