LMX2364 National Semiconductor Corporation, LMX2364 Datasheet - Page 34

• Manufacturer Part Number: LMX2364
• Description: 2.6 Ghz Pllatinum Fractional Rf Frequency Synthesizer With 850 Mhz Integer If Frequency Synthesizer
• Manufacturer: National Semiconductor Corporation

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Supplemental Information
3.0 USE OF THE DIGITAL LOCK DETECT FUNCTION
The Lock Detect Digital Filter compares the difference be-
tween the phase of the inputs of the phase detector to a RC
generated delay of approximately 15nS. To enter the locked
state (Lock = HIGH) the phase error must be less than the
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15nS RC delay for 5 consecutive reference cycles. Once in
lock (Lock = HIGH), the RC delay is changed to approxi-
mately 30nS. To exit the locked state (Lock = LOW), the
phase error must become greater than the 30nS RC delay.
When the PLL is in the power down mode, Lock is forced
LOW. A flow chart of the digital filter is shown below.
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