Table 6.10. SCC Register Fields
idxy_ss_ena
Spread spectrum enable. This is the only bank configuration field which may be changed dynamical-
ly while the bank is selected as the active bank. Users may freely enable/disable spread spectrum.
0 = spread spectrum disabled
1 = spread spectrum enabled
idxy_ss_mode
Spread spectrum mode.
0 = disabled
1 = center
2 = invalid
3 = down
idxy_ss_clk_num
Number of output clocks for each frequency step.
idxy_ss_step_num
Number of frequency steps in one quarter SSC modulation period, allows for frequency step every
output clock.
idxy_ss_step_intg
Divide ratio spread step size.
idxy_ss_step_res
Numerator of spread step size error term.
idxy_ss_step_den
Denominator of spread step size error term.
To enable SSC,
idxy_ss_ena
needs to be set and the right mode selected in
idxy_ss_mode
. The number of output clocks in each
frequency step,
idxy_ss_clk_num
, needs to be set to 1 and
idxy_ss_step_den
is the same as
idxy_den
and
idxy_ss_step_intg
is
always zero.
The following flow needs to be followed to program the registers into Si5332:
1. Write 0x01h to register 0x06h and put the Si5332 into the READY state.
2. Write all the relevant registers as calculated from the steps above.
3. Ensure that the valid input clocks are available for the Si5332 to attempt a PLL lock.
4. Write 0x02h to register 0x06h and put the Si5332 into the ACTIVE state.
Si5332-AM1/2/3 Automotive Grade Device Reference Manual
Programming the Volatile Memory (Registers)
silabs.com
| Building a more connected world.
Preliminary Rev. 0.1 | 29