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Original question:

LSF0108-Q1: About LSF0108-Q1

LSF0108-Q1: I'm having trouble connecting I2S to LSF0108.

?? ?
Prodigy 30 points
Part Number: LSF0108-Q1
Other Parts Discussed in Thread: TXU0304-Q1, LSF0102-Q1, TXU0104-Q1, TXU0204-Q1, LSF0108, TAS6424-Q1, TAS6424

Tool/software:

Dear Clemens Ladisch

I have a problem with I2S connection. Please help me.

e2e.ti.com/.../5841959

  • 0
    Guru 314230 points

    The LSF is a passive switch; the device that is driving the line must be able to sink the current through both pull-up resistors. When the current is too high, the VOL of your device increases (as you have seen).

    When you have a push/pull output, then you do not need a pull-up at the LSF input pin.

    The LSF has open-drain outputs, so you always need pull-ups at the outputs. The minimum pull-up value is determined by the drive strength of your device (here, the AP). The maximum pull-up value is determined by the capacitance of the signal line, i.e., by its length; if the resistors is too weak, the rising edges are too slow. For very long lines or when you have cables/connectors, it might not be possible to find a resistor that conforms to both limits.

    Unidirectional, buffered translators like the TXU0104-Q1/TXU0204-Q1/TXU0304-Q1 would be much more robust. You would need a bidirectional translator like the LSF0102-Q1 only for the I²C signals.

    I do not know what "clock fault" actually means; it might be possible that you're using a wrong frequency.

  • 0 in reply to Clemens Ladisch
    Prodigy 30 points

    Dear clemens Ladisch 

    thanks for your reply.

    Our board is cpu(exynos) + lsf0108(level shifter) + tas6424-q1(audio amp)

    Currently, the audio amp is generating a "clock fault" interrupt. So I'm currently contacting Ti export.

    Please help me. I want to know what is causing clock fault (Reg 0x11) in tas6424 amp.

  • 0 in reply to ?? ?
    TI__Mastermind 36806 points

    Hello,

    Please help confirm if Clemens' suggestions were implemented and benefit- as the concern appears related to an VOL/ speed tradeoff issue or using the wrong frequency. 

    Regards,

    Jack

  • 0 in reply to Jack Guan
    Prodigy 30 points

    Dear Jack Guan

    Thanks for your help.
    I will forward this to the hw team and ask if Clemens Ladisch's suggestion is applicable to our board. I am glad that this issue is not a software issue. Our hw said it is a software team issue.

  • 0 in reply to ?? ?
    TI__Mastermind 36806 points

    Hi,

    No problem. Please update us if any new concerns. 

    Regards,

    Jack 

  • 0 in reply to Jack Guan
    Prodigy 30 points

    Thank you. The hw team is not accepting the fact that the level shifter needs to be changed. Although it is difficult, I have conveyed the opinion of the Ti experts.

    The hw team is reporting the fault interrupt (clock fault) of tas6424 as a problem caused by the register setting in the sw.
    I will ask again if there are any other changes.

  • 0 in reply to ?? ?
    TI__Mastermind 36806 points

    Hi,

    Thanks for the update. Feel free to create new thread new issue arises with the TI components.

    Regards,

    Jack