4. External Reference Input (XA/XB)
An external timing reference (48 MHz XTAL) is used in combination with the internal oscillator to produce an ultra-low jitter reference
clock for the DSPLL and for providing a stable reference for the free-run and holdover modes. The Si5348-E-EVB can also accommo-
date an external reference clock instead of a crystal. To evaluate the device with an external REFCLK, C111 and C113 must be popula-
ted and XTAL Y1 removed (see figure below). The REFCLK can then be applied to SMA connectors J39 and J40.
Figure 4.1. External Reference Input Circuit
UG362: Si5348-E Evaluation Board User's Guide
External Reference Input (XA/XB)
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