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LMK05318B: DPLL configuration script

Andrea Pastega
Prodigy 120 points
Part Number: LMK05318B

Tool/software:

Hello,

we would be able to configure an LMK05318B employed in our product with "any" PRIREF frequency (and related bandwidth).

Starting point would be the reference frequency itself, read from a user configurable file (e.g. 1Hz, 10Mhz, 10.23MHz, 40MHz, etc).

We need to compute all relevant registers of DPLL to program it to operate with specified reference frequency.

Doing a little of retro-engineering of fractional divider register, I was able to understand how to change frequency. 

However, changing frequency also requires a different bandwidth configuration (1/100 ratio with reference frequency). 

So basically we need to know how configuration script in TICSPRO operates, so we can compute the values for the other registers.

Or as alternative, a complete explanation of DPLL related registers, as programming manual is missing details about these registers.

Any help for this?

Thanks

Andrea

  • 0
    TI__Mastermind 18380 points

    Hello, 

    The team is out of office for the holiday weekend. Please expect a response on Monday.

    Thanks, 

    Kadeem 

  • 0
    TI__Prodigy 550 points

    Hello Andrea,

    The configuration script in TICSPRO cannot be shared but there is a workaround solution.

    For the registers impacting the DPLL what matters for correctly configuring the device is the TDC frequency, since there are dividers between the PRIREF frequency and the TDC frequency we can divide the input to certain TDC frequencies. We can use TICSPRO to calculate "x" different DPLL register configurations for the different TDC frequencies we can divide to. This allows us to have multiple different PRIREF frequencies that have the same TDC frequency which lets us use one DPLL register configuration for multiple input frequencies.

    Although this may still have a range of possible TDC frequency values depending on the range of input frequencies. But if your TDC frequency is within 5% of the target TDC frequency you should be able to use the same DPLL configuration even if the TDC frequency is only slightly off.

    Is there a range of values for possible PRIREF frequencies?

    Best Wishes,
    Kyle Yamabe