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TXS02612: TXS02612

Part Number: TXS02612
Hello Sir
Please check as below inquire.
When applying the TXS02612R part below,

Some SD cards are not recognized.

 

Removing TXS02612R and connecting it to SD1 Port will work well.

I would like to ask you to check if there is any problem in the circuit


Some SD cards are not recognized.

 

Removing TXS02612R and connecting it to SD1 Port will work well.

I would like to ask you to check if there is any problem in the circuit
  • Hi,

    The internal block diagram of the device is shown in the datasheet page 4.
    The IOs have internal pullup resistance, the value of which depends on the A/B port voltage level. I see from the schematic that there are external pullup resistors on the device on the A ports. and there are pulldown resistors on the output of B ports as well as seen from the one from the right.
    Again, this will cause a voltage divider which is not ideal. I would suggest you to remove the external pulldown and pullup resistors.
    I will expect it to work then. Please let me know.

    Also, curious to know the B1 ports are working without issues? if there are scopeshots of the B0 ports, please do send out.
  • I have attached an app note about the pullup and pulldown effects on the TXS type of devices :
    www.ti.com/.../scea054a.pdf
  • Thanks for your reply,

    I have a misunderstood part by passing a schematic to a picture.

    Pdf file will be sent back to the schematic file.

    - The part described by pull down resistance of reply contents is varistor (EZJZOV500AA: 3pF).

     

    In addition, when you check the part of the SD below,

    As shown in the figure below, the HS SD card works but the UHS SD card does not work.

    - As TI replies, remove the external pull up of R56 ~ R60 and remove the varistor of VR415 ~ VR420

    The SD card of UHS does not work even when checking.

     

    Please check again.

  • What is the operating speed on the UHS? The device is not setup for high speed data transfer for SD 3.0 spec.
    The speed is also limited due to the internal pullup resistors; especially at low voltages. Do you have the scopeshots of the waveform being read at the output of the device? Are there long transmission lines from the device to the reading point? The internal pullup and the external parasitic loading will limit the data transfer speeds.
    Please let me know
  • Thanks for your reply.

    First of all, about the inquiry below



    1. In case of UHS Card, sd clock frequency is 100Mhz, and the waveform measured by scope will be transmitted.



    - Waveform comparison when inserting SD Card (UHS).



    2. The distance of the transmission line is shortened to 20mm between the B0 port of TXS02612 and the SD socket,



    B1 port is 500mm by shielding cable.



    However, the UHS card is not recognized even at the short B0 port.



    3. If there are additional components available for internal pull-up resistors or UHS SD



    please check.

  • Thank you for the reply.
    From the datasheet, the max frequency the clock can support is 60Mhz. The data and command line is also rated at 120Mbps (60Mhz).
    The 100Mhz rating is more than the rated spec the device is able to handle.
    the shielding cable would add high parasitic loading on the TXS output; much more than the device is able to drive.
    We, unfortunately, do not have device currently to handle high speed SD card 3.0 version