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SN74AUC07: Looking for proper device for SD card interface re-driver for smart phone folder type.

Jung-Ho Seo
Expert 5325 points
Part Number: SN74AUC07
Other Parts Discussed in Thread: SN74AUC244, SN74LVC244A, SN74AUC245

Dear experts,

Customer is looking for re-driver to connect SD card 6 pins (Data0~3, CMD,CLK).

Currently, they have problem with High speed(200MHz) communication due to long line trace for board to board connection .

I recommended SN74AUC07 but it's size is 3.5x3.5. customer said it is big..

Required data rate : 200MHz over, smaller size, 6 pin re-driver.

Would you recommend smaller device for this application ?

Thanks,

JH Seo.

  • 0
    TI__Mastermind 24665 points
    Hello JH,

    Please note that since the AUC07 device is an open drain output device, there will be 6 resistors required as pullups on the output.
    Our recommendation would be to use the SN74AUC244 device. This comes in an RGY package and can handle the speeds that you need. The package is slightly larger than the 3.5 x 3.5 suggested, but does not require the pullup resistors on the output, so ultimately would take less space.

    If you are really interested in size, we can also recommmend the SN74LVC244A in the X1QFN (RWP) package. This device has enough channels and comes in a very small package. This device is not explicitly able to handle 200MHz signalling, but may be able to in practice, so further evaluation would be required.

    Best,
    Michael
  • 0 in reply to Michael J Schultis
    TI__Expert 5325 points

    hI Michael,

    thanks for feedback.

    Sorry. I did not know that they need bi-directional device because SDIO data is bi-directional. is there bi-directional re-driver ?

    As for 200MHz data rate, how can we know it based on datasheet ? no comment on datasheet about max data rate..

    Thanks,

    JH Seo.

  • 0 in reply to Jung-Ho Seo
    TI__Expert 5325 points
    Hi Michael,
    I found SN74AUC245(3x4 BGA) which can support bi-directional.
    5ch are bi-direction. 4 data lines and CMD.. so only Clk is from processor.
    In this case, Is it no problem with timing between CLK and Data(0~3)/CMD ?
    How is max data rate in this device ?
    Would you feedback on this ?

    Thanks,
    JH Seo.
  • 0 in reply to Jung-Ho Seo
    TI__Mastermind 24665 points
    Hello JH,

    While the SN74AUC245 does not have a rated frequency, the AUC family was designed for >200MHz operation.
    This should be a suitable device for this application.
    Specifically, the orderable you would be looking for is SN74AUC245ZQNR.

    Best,
    Michael