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LMK04906

David Escandon
Expert 2175 points
Other Parts Discussed in Thread: LMK04906

TI Team,

I plan to use the LMK04906 and I have a couple of questions regarding its operation.

I'd like the ability to bypass the VCO and output the VCXO clock, or another external clock, under some conditions. There are two methods I see to accomplish this. First, CLKOUT3 and CLKOUT4 appear to have OSCIN muxes which I can use. Second, CLKIN1/Fin appears to allow direct distribution of the input clock to the outputs. Can I loop back OSCOUT to CLKIN1/Fin and disable the 1st charge pump to output the VCXO clock to all outputs?

Can this be done? Is this not recommended for any reason?

-David

  • 0
    TI__Mastermind 32575 points

    MODE=11 supports Single PLL2 with External VC(X)O to allow all 6 CLKout pairs and OSCout pair to have output clocks derived from the VCXO frequency. See Figure 5 for the simplified diagram, except the Internal VCO is disabled and substituted by the external VCXO clock applied to the FIN port.  Table 1 summarizes that in MODE=11, PLL1 is not used and 0-delay mode is not available. Also, CLKIN0 and CLKIN1 ref inputs to PLL1 are not used in this MODE and the reference clock input is applied to the OSCIN port.

    Regards,

    Alan