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LDC1612-Q1: About SNOA944 Optimizing L Measurement Resolution for the LDC161x and LDC1101

Part Number: LDC1612-Q1

Hello, 

Figure 5. How do you calculate the graph with LDC161x Resolution with fREF = 40 MHz?

  • My understanding is these curves cam from measured data.
    We do not have any equations to share.

    Regards,
    John

  • Dear John Miller.

    Thank you for your quick reply.

    I am surprised to find that the graph is obtained from the actual measurement results.

    About "Table 3. LDC161x Resolution of a 1% fSENSOR Variation with RCOUNT = 0xFFFF"

    Are the unique output codes in Table 3 also the actual measurement result?

    I've always wondered how to get this unique code.

    In my method, the graph of RCOUNT = 0xffff in Fig. 5 is as follows.

    At each frequency change

    OUTPUT CODE / UNIQUE OUTPUT CODES x 40MHz / 2 ^28 

    However, I couldn't complete Graph 5 because I didn't know how to find UNIQUE OUTPUT CODES in other RCOUNT settings.

    So I asked this question this time.

    Best regards

  • The plot styles are based on a limited number of points, so my strong suspicion is they are based on measured data, not calculations.
    There's no guidance to offer at this time on calculating the relationship between the resolution and the contributing factors, like RCOUNT and the number of unique codes, etc.

    I will work on this and update the thread when there is something to report.

    If it helps, one of our app notes (Power Reduction Techniques...) shows an equation that can serve as a starting point for the RCOUNT setting.
    See equation 4:

    RCOUNT = 2^(N-3) where N is the required resolution in bits.