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LSF0108: SPI Quad mode support

Antony Lin
Genius 13480 points
Part Number: LSF0108
Other Parts Discussed in Thread: LSF-EVM

Hi,

We need a 6-bit level shifter to support quad mode SPI between AMD CPU (CL around 10pF / SPI @ 1.8V) and SPI flash (W25Q256FV with CL around 30pF / SPI @ 3.3V).  Among the 6 signals, 4 data signals are bi-directional.  CLK and CS signals are uni-directional.  The max speed needs to be support is 66.6MHz.

Would LSF0108 be a right solution for this?  Or any other part is preferred?

Thanks!

Antony

  • 0
    TI__Guru* 96591 points
    LSF0108 will work in this application, however it will require careful design. The device needs to be placed as close (physically) as possible to the high-side device to minimize trace capacitance (and maximize speed). Additionally, all drivers on the line need to be able to sink ~15mA in order for this to work.

    We will be releasing a video series that goes into detail on this in the next two weeks (hopefully by the end of this week), which will be very helpful to you I think.
  • 0 in reply to Emrys Maier
    TI__Genius 13480 points

    HI Emrys,

    Regarding the capability to sink 15mA that you mentioned, does it mean customer needs to refer to "Table 4. Pull-up Resistor Values" in LSF0108 datasheet?  May you explain why 15mA instead of 10mA or 3mA is suggested here?

    Thanks!

    Antony

  • 0 in reply to Antony Lin
    TI__Guru* 96591 points
    I recommend 15mA due to the speed requirement. 66 MHz is towards the top end of the LSF's capabilities. Have you seen our LSF-EVM? http://www.ti.com/tool/LSF-EVM