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7.3 Dynamic Changes to Output Frequencies without Changing PLL Settings
This section applies to the following scenario:
1. A CBPro generated register map "was" used to program either the volatile or the non-volatile memory of a Si5340/1. Changes to
output frequencies without changing the PLL settings are desired.
2. The CBPro project file can be used to look for the VCO frequency (FVCO), Ry, Nx values for each OUTy in the design report
and/or the datasheet addendum.
OUTy = FVCO/(Nx * Ry)
Solve for Nx based on the desired OUTy. The Nx dividers can be digitally controlled to so that all outputs connected to the Nx divider
change frequency in real time without any transition glitches. There are two ways to control the Nx divider to accomplish this task:
1. Use the Frequency Increment/Decrement Pins or register bits.
2. Write directly to the numerator or denominator of the Nx divider.
The details of both methods are covered in
6.1 Using the N Dividers for DCO Applications
.
7.4 Dynamic Changes to Output Frequencies while Changing PLL Settings Using a CBPro Register Map
This section applies to the following scenario:
1. A CBPro generated register map "is" used to program either the voltatile or the non-volatile memory of a Si5340/1.
2. This needs a register write sequence provided in the CBPro export section as shown below.
Figure 7.1. CBPro Register Write Sequence While Changing PLL Settings
Si5341, Si5340 Rev D Family Reference Manual • Dynamic PLL Changes
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
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Rev. 1.3 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • July 26, 2021
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