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TS3A27518E: Design issue for TS3A27518E

Zhang Liang
Genius 4125 points
Part Number: TS3A27518E
Other Parts Discussed in Thread: TMUX1208,

Hi,

We design the CPU SPI switch and we consider to use the TS3A27518E or TMUX1208, the SPI rate is 12.5M

But now we are afraid of the mulit-layer PCB will generate shock and the single don't synchronous, please advise the design as below is available or not, and which one is the better between TS3A27518E

and TMUX1208, thanks.

QSPI信号信号框图.pdf

  • 0
    TI__Mastermind 35168 points

    Hey Zhang,

    I wouldn't recommend cascading 4 multiplexers. The parasitic affects would probably too great for you to be able to get useful data. The signal would be significantly slower and the bandwidth will be reduced heavily.

    Was the idea for the TMUX1208 to use 6 of them and mux through the 6 traces of the 5CPU's? I would recommend a solution as that more than cascading 4 TS3A27518E solution.

    Thanks,
    Rami

  • 0 in reply to Rami Mooti1
    Genius 4125 points

    Hi Raml,

    Thanks for your kindly support.

    And I consider to use the 6 traces of TMUX1208, please advise if the below design is available or not?

  • 0 in reply to Zhang Liang
    TI__Mastermind 46888 points

    Hi Zhang,

    This design makes more sense than the first. You will have a couple of unused IO's because you are using an 8:1 device, but now you will not run into cascading problems that effect the overall BW of the system.

    I am assuming you have 6 TMUX1208's for 6 data lines (IO0, IO1, IO2, IO3, SCK, CS). This way you can mux the SPI signals to multiple SPI CPU's (up to 8 SPI CPU's because 8:1 configuration). This design seems to be an improvement of the first one you provided. 

    Regards,

    Tyler