SI5348 Datasheet, PDF (9/54 Pages) Silicon Laboratories – Network Synchronizer for SyncE/ 1588 PTP Telecom Boundary (T-BC) and Slave (T-SC) Clocks

Si5348 Rev D Data Sheet
Functional Description
3.6.2 External Reference (REF/REFb)
The external reference at the REF/REFb pins is used to determine output frequency accuracy and stability during free-run and holdover
modes. This reference is usually from a TCXO or OCXO and can be connected differentially or single-ended as shown in the figure
below:
5 – 250 MHz TCXO/
OCXO
5 – 250 MHz TCXO/
OCXO
100
REF REFb
REF REFb
Si5348
Differential External
Reference Connection
Si5348
Single-ended External
Reference Connection
Figure 3.6. External Reference Connections
3.7 Inputs (IN0, IN1, IN2, IN3, IN4)
There are three inputs (IN0, IN1, and IN2) that can be used to synchronize any of the DSPLLs. The inputs accept both differential and
single-ended clocks. A crosspoint between the inputs and the DSPLLs allows inputs IN0-IN2 to connect to any of the DSPLLs as shown
in the figure below. DSPLL D has two additional inputs (IN3-IN4) that can be manually selected. IN3 and IN4 are CMOS only inputs. If
both IN3 and IN4 are used, they must be the same frequency.
Si5348
IN0
IN0b
÷
P0n
P0d
Input
Crosspoint
0
1
2
DSPLL
A
IN1
IN1b
÷
P1n
P1d
0
DSPLL
1
2
C
IN2
IN2b
IN3
IN4
÷
P2n
P2d
0
1
2
DSPLL
D
3
4
Figure 3.7. DSPLL Input Selection Crosspoint
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