SI5350C-B Datasheet, PDF (13/31 Pages) Silicon Laboratories – FACTORY-PROGRAMMABLE ANY-FREQUENCY CMOS CLOCK GENERATOR

and FS1 selects the frequency on CLK1.
FS0
Bit Level
0
1
Free-running Frequency
F1_0:
F2_0:
74.25 MHz
74.25 _MHz
1.001
FS1
Bit Level
0
1
Synchronous Frequency
F1_1:
F2_1:
24.576 MHz
22.5792 MHz
Si5350C-B
27 MHz
XA
XB
Free-running Clock
FS0
74.25 MHz or ^74.25 MHz
CLK0
1.001
FS1
54MHz
Si5350C
CLKIN
Synchronous Clock
CLK1 24.576 MHz or 22.5792 MHz
Video/Audio
Processor
Figure 7. Example of Generating Two Clock Frequencies from the Same Clock Output
Up to two frequency select pins are available on the Si5350C. Each of the frequency select pins can be linked to
any of the clock outputs as shown in Figure 8. For example, FS_0 can be linked to control clock frequency
selection on CLK0, CLK3, and CLK5; FS_1 can be used to control clock frequency selection on CLK1, CLK2, and
CLK4. Any other combination is also possible. The frequency select feature is not available for CLKs 6 and 7.
The Si5350C uses control circuitry to ensure that frequency changes are glitchless. This ensures that the clock
always completes its last cycle before starting a new clock cycle of a different frequency.
FS_0 Output Frequency
0 F1_0, F1_3, F1_5
1 F2_0, F2_3, F2_5
FS_1 Output Frequency
0 F1_1, F1_2, F1_4
1 F2_1, F2_2, F2_4
Customizable FS Control
FS
MultiSynth 0
CLK0
FS_0
FS
MultiSynth 1
FS
MultiSynth 2
FS
MultiSynth 3
CLK1
CLK2
CLK3
FS_1
FS
MultiSynth 4
MultiSynth 5
FS
CLK4
CLK5
Cannot be controlled
by FS pins
CLK6
CLK7
Glitchless Frequency Changes
New frequency starts
at its leading edge
Frequency_A
CLKx
Frequency_B
Frequency_A
Full cycle completes before
changing to a new frequency
Figure 8. Example Configuration of a Pin-Controlled Frequency Select (FS)
Rev. 1.0
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