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TXS02612: Support for SD card High-Speed Mode

Daisuke Maeda
Guru 20425 points

Part Number: TXS02612
Other Parts Discussed in Thread: TMUX1574, AM6442, TXS0206A

Does TXS02612 support SD card High-Speed Mode?

When VCCA = 3.3 V and VCCB = 3.3 V:
The propagation delay (tPD) of clock from controller to SD card (CLKA to CLKB) is 3.5 ns (max). 
The propagation delay (tPD) of data from SD card to controller (DATB to DATA) is 3 ns (max).

For SD Card High-Speed Mode:
The Output Delay Time during Data Transfer Mode (tODLY) is 14 ns (max).

The total of these delays is 20.5 ns, which exceeds the 20 ns clock period of High-Speed Mode (50 MHz).

The TXS02612 is unlikely to support SD card High-Speed Mode.

Best regards,

Daisuke

 

  • 0
    TI__Guru 58701 points

    Hi Maeda-san,

    Let me get back to you on this, I am still looking into it.

    Thanks,

    Jack

  • 0 in reply to Jack Guan
    Guru 20425 points

    Hi Jack-san,

    Thank you for your reply.

    If there is an alternative device that can reliably support SD card High-Speed Mode, I would appreciate it if you could suggest that first.

    Best regards,

    Daisuke

  • 0 in reply to Jack Guan
    Guru 20425 points

    Hi Jack-san,

    Thank you for your reply.

    Daisuke Maeda said:
    If there is an alternative device that can reliably support SD card High-Speed Mode, I would appreciate it if you could suggest that first.

    Our customer want to use an SD card in High-Speed mode (3.3 V) and an SDIO device (1.8 V) by switching between them. Since there appears to be no device that can switch SDIO ports in the same way as the TXS02612, I believe the solution would consist of a combination of an analog switch and a level shifter.

    Best regards,

    Daisuke

  • 0 in reply to Jack Guan
    Guru 20425 points

    Hi Jack-san,

    Daisuke Maeda said:
    Our customer want to use an SD card in High-Speed mode (3.3 V) and an SDIO device (1.8 V) by switching between them. Since there appears to be no device that can switch SDIO ports in the same way as the TXS02612, I believe the solution would consist of a combination of an analog switch and a level shifter.

    I would appreciate it if you could suggest a solution that supports High-Speed Mode.

    For example, TMUX1574 is an analog switch with bidirectional signal paths and propagation delay of less than 100 ps. By using two of them, it should be possible to switch between two SDIO ports.
    However, I have not been able to find a level shifter with bidirectional signal paths and small propagation delay.

    For SD Card High-Speed Mode:
    Output Delay Time during Data Transfer Mode (tODLY) is 14 ns (max).

    For SDIO 2.0 Secondary High Speed Mode:
    SDIO_DATA, clock to output delay (tod) is 13 ns (max)

    For SD card and SDIO host controller (AM6442):
    Setup time, data valid before clock rising edge is 2.15 ns (min)

    For an analog switch and a level shifter:
    Total of propagation delay (Clock from controller to SD card + Data from SD card to controller) must be less than 20 ns - 13 ns - 2.15 ns = 4.85 ns.

    Best regards,

    Daisuke

  • 0 in reply to Daisuke Maeda
    TI__Guru 58701 points

    Hi Maeda-san,

    Let me follow up tomorrow.

    Regards,

    Jack

  • 0 in reply to Jack Guan
    TI__Guru 58701 points

    Hi Maeda-san,

    Thanks for your patience on this one. TXS0206A and TXS02612 are the high speed SD card translators in the portfolio supporting high speed mode (50MHz CLK) if VCCA/ VCCB condition is satisfied, similar to the below for TXS0206A:

    However if you concerns are for 1.8V to 3.3V and not  switch use care where VCCA=3.3V and VCCB= 3.3V, the prop delay concerns would be valid and the alternative solution to which you have suggested is a more valid approach. Please note that the TXS02612 does redrive/ buffer the CLK edge however and the MUX solution would be a passFET based solution.

    Regards,

    Jack