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LMX2595: MUXout pin issue (readback funtion not working)

Part Number: LMX2595

I am working with the LMX2595.

Regarding the SPI connection, I am able to write it, but it seems impossible to read any data from it so far.

I know that the pin to read data is MUXOUT but I have not seen any data from it. However, I can write it and I sure because enabling and disabling the powerdown bit I see a noticeable difference in power consumption (for instance).

So, could you please confirm me that the right edge for SDI and MUXout are the ones I have painted in red (SDI) and green (MUXout)  ¿?


Do you have any other suggestion or trick ¿?


  • Hi Gerardo,

    Read back data should be sampled with the rising edge of SCK. 

    To read back, make sure the R/W bit = 1.

  • Hi Noel,

    Thanks for your support. However, I guess the sampling edge is not the rising but the falling. It is working now and I'm using the falling edge of SCK as I indicated above (also it is said in the datasheet just below of that Figure 2). I guess that the trick was that it is needed to overwrite register 0 (all bis '0') to start MUXout pin working us SPI readback. This should not be needed according to datasheet, but it works.