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Revised
-
December 2013
LMK04906 Family: Low-Noise Clock Jitter with Dual Loop PLLs
SNAU126A
27
Copyright © 2013, Texas Instruments Incorporated
VCO Frequency (MHz)
n/a
The VCO Frequency should be the
OSCin frequency, except when operating
in Dual PLL with 0-delay feedback. This
value is calculated as:
VCO Freq (OSCin freq) = PLL1 PDF *
PLL1_N.
In Dual PLL mode with 0-delay feedback,
the VCO frequency should be set to the
feedback clock input frequency. See the
section Setting the PLL1 VCO
Frequency and PLL2 Reference
Frequency for details.
R Counter
PLL1_R
PLL1 R Counter value (1 to 16383).
N Counter
PLL1_N
PLL1 N Counter value (1 to 16383).
Phase Detector Polarity PLL1_CP_POL
PLL1 Phase Detector Polarity.
Click on the polarity sign to toggle
polarity “+” or “–”.
Charge Pump Gain
PLL1_CP_GAIN
PLL1 Charge Pump Gain.
Left-click/right-click to increase/decrease
charge pump gain (100, 200, 400, 1600
uA).
Charge Pump State
PLL1_CP_TRI
PLL1 Charge Pump State.
Click to toggle between Active and Tri-
State.
Setting the PLL1 VCO Frequency and PLL2 Reference Frequency
When operating in Dual PLL mode without 0-delay feedback, the VCO frequency value
on the
PLL1
tab must match the Reference Oscillator (OSCin) frequency value on the
PLL2
tab; otherwise, the one or both PLLs may be out of lock. Updating the Reference
Oscillator frequency on the
PLL2
tab will automatically update the value of
OSCin_FREQ on the
Bits/Pins
tab.