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TXS0108E: SPI Communications Problems

Ko yohan
Prodigy 20 points
Part Number: TXS0108E
Other Parts Discussed in Thread: TXB0108

Hello.

I tried to use SD card in MCU using TXS0108 IC.

However, you have noticed the following problems with the SClK line of SPI communications.

Am I designing the circuit correctly?

I attach the circuit diagram that I used and the problem oscilloscope waveform.

Thanks.

  • 0
    TI__Guru 59160 points
    Hi Ko,

    You have the pullup resistor which is not very clear to me, but it seems like it is 4.7k.
    The TXS internally has pullup resistor and hence the external pull up is not required. Please remove it to see if the signal integrity improves.

    Alternatively, you could consider using TXB0108 which is suitable for SPI communications.
  • 0 in reply to ShreyasRao
    Prodigy 20 points
    Thank you for your answer.

    But my problem is not solved yet.

    Except for 4.7 resistance, the same waveform appears.

    It works normally when inserting other general data in MCU.

    Does not work only when you enter the SCLK signal for SPI.

    Do I have any problems?

    Thank you.
  • 0 in reply to Ko yohan
    TI__Guru 59160 points
    Hi Ko,

    It seems to me that the driver (MCU) doesnt have enough drive strength to drive the SPI signal. do you have the updated scope shot? Is there no improvement from previous measurement to present measurement without the pullup resistors?
    i know this might be a hassle but would you consider switching to TXB0108 and try again?