JAJSS15 November 2023 LMK3H0102
ADVANCE INFORMATION
FOD0 supports spread-spectrum clocking (SSC). SSC can be used to reduce peak radiated emissions by modulating the output frequency. When SSC is enabled (R4[0] = 1), any outputs that are sourced from FOD0 have SSC. Both down-spread modulation (R4[1] = 0) and center-spread modulation (R4[1] = 1) are available. The LMK3H0102 has four built-in down-spread SSC options, as well as a custom SSC option. Table 7-6 details the register settings for the pre-configured SSC options. If Custom SSC is selected, then Registers R4 and R5 must be configured to set the modulation depth. If the edge combiner is used, then spread-spectrum clocking must be disabled.
R9[11:9] | Down-spread SSC Depth |
---|---|
0x0 | Custom, based on R4 and R5 |
0x1 | –0.10% |
0x2 | –0.25% |
0x3 | –0.30% |
0x4 | –0.50% |
All other values | Reserved |
Use Equation 5 and Equation 6 to determine the SSC_STEPS (R4[14:2]) register settings, and use Equation 7 to determine the SSC_STEP_SIZE (R5) settings.
where:
where:
If using a mix of SSC on one output and no SSC on a different output, there can be crosstalk between the two outputs. Contact TI to request measurement data for a specific configuration when configuring SSC on only a single output.