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SN74CBTLV3257: Want to use 1 SPI flash memory for 2 MCUs.

Chase Jeong
Genius 4670 points
Part Number: SN74CBTLV3257
Other Parts Discussed in Thread: TS3A27518E, TMUX1574, TMUX1575

Hello TI experts,

My customer wants to use 1 SPI flash for 2 MCUs, I think they have to use analog SPDT switch for it.

in my searching, SN74CBTLV3257 is suitable for it. but I need your confirmation.

In addition, I found a thread on E2E ;

https://e2e.ti.com/support/switches-multiplexers-group/switches-multiplexers/f/switches-multiplexers-forum/647139/ts3a27518e-q1-about-switching-application-of-spi-flash-signal

Is it okay to check the spec that have only over 4 channels and bandwidth?

(cause TS3A27518E is just a SPDT switch, not noticed for SPI interface)

please check this issue. Thanks.

Best regards,

Chase

  • 0
    TI__Intellectual 2694 points

    Hi Chase,

    For standard SPI operation 4channel SPDT (2:1) switch is needed. This will have CLK, CS/, DATAIN, DATAOUT. We would recommend our newer TMUX1574 device in this case.

    For QSPI operation 6channel SPDT (2:1) switch is needed. This will have CLK, CS/, 4 I/O lines for data. We would recommend the TS3A27518E device in this case.

    Hope this helps.

    Thank you,

    Regards,
    Sandesh

  • 0 in reply to Sandesh Rawool
    Genius 4670 points

    Dear Sandesh,

    Thank you for your support.

    Actually I agree with your opinion, TMUX1574 is better because it is new device. but as you know there are no online stocks on TI.com and delivery is too long for this part.

    so I want to suggest SN74CBTLV3257 to my customer because it has plenty of stocks on TI com even delivery is too long.

    could you confirm that there are no general problems with SN74CBTLV3257 to implement that function?

    Best regards,

    Chase

  • 0 in reply to Chase Jeong
    TI__Genius 10974 points

    Hi Chase,

    The SN74CBTLV3257 could be a valid option as long as your bandwidth requirements are met by this device (100MHz) and also the voltage node it not greater than 3.3V.

    In addition, you can also look into the TMUX1575 which would probably be more suited for this application if you are willing to use a WCSP package.

    Thanks!

    Bryan