SI5347-46 Datasheet, PDF (8/13 Pages) Silicon Laboratories – Data Sheet Errata for Product Revision B

6. Exit From Holdover Ramp Feature Not Functional
Data Sheet Errata for Product Revision B
Exit From Holdover Ramp Feature Not Functional
Description
The exit from holdover ramp feature is not functional.
Impact
Using the ramp feature to lock to a new input frequency while exiting from holdover does not function. The user cannot select holdover
modes that exit using a frequency ramp. Instead, the exit from holdover frequency rate of change needs to be governed by the loop
bandwidth.
Workaround
When exiting from holdover, use a loop bandwidth-determined exit from holdover. For example, loop bandwidth-controlled exit from
holdover can be configured to meet the requirements of Stratum 3 and many other standards. To do this, ensure
HOLD_RAMP_BYP_PLLA, HOLD_RAMP_BYP_PLLB, HOLD_RAMP_BYP_PLLC, and HOLD_RAMP_BYP_PLLD are set high at loca-
tions 0x042C[3], 0x052C[3], and 0x062D[3). These registers have been set correctly since CBPro v1.0 was released.
Resolution
This erratum will be fixed in the next silicon revision.
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