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Original question:

LSF0204: could the device support QPSI?

LSF0204: QSPI support

R.Fukunaga
Expert 2505 points
Part Number: LSF0204

Tool/software:

Hi all,

I would like to use LSF0204DPWR in QSPI I/F line.

1. I want to use it in QSPI I/F(Bidirectional, no direction switching signal). Can I use it without any problem?

2. In case of QSPI, is pull-up resistor unnecessary in signal line?

If I want to add pulldown resistor, should I determine the constant referring to Table 10-3 in the datasheet?

Best Regard

Ryusuke

  • +1
    Guru 317000 points

    1. The LSF can work. It requires strong pull-up resistors to reach high speeds, so the devices must be able to sink that current.

    2. Pull-up resistors must be used on the higher-voltage side, and should be used on the lower-voltage side.

    3. Pull-down resistors must not be used.

    Table 10-3 assumes that you already know what pull-up current you want. But that depends on the desired speed and the capacitance of the devices and the traces

    You should use the TXB (without any pull-up/-down resistors), and you should not use long traces/cables.

  • 0 in reply to Clemens Ladisch
    Expert 2505 points

    Hi Clemens,

    1) I understand that the LSF can drive QSPI, but it needs a pull-up resistor on the high voltage side.

    What is the constant of strong pull-up resistor? Should I use the following diagram to determine the constant?

    2) Do you recommend the TXB series?

    Best Regards,

    Ryusuke

  • +1 in reply to R.Fukunaga
    Guru 317000 points

    1. The size of the pull-up resistor depends on the desired speed and the capacitance of the devices and the traces on your actual board.

    2. Yes. Please note that the TXB also has restrictions; see my first answer.