MMC2114 MOTOROLA [Motorola, Inc], MMC2114 Datasheet - Page 260

• Manufacturer Part Number: MMC2114
• Description: M CORE Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

Clock Module
Advance Information
260
WITH TIGHT LOCK
CRITERIA
START
NUMBER OF FEEDBACK
REFERENCE CYCLES
CYCLES ELAPSED
After lock is detected, the lock circuit continues to monitor the reference
and feedback frequencies using the alternate count and compare
process. If the counters do not match at any comparison time, then the
LOCK flag is cleared to indicate that the PLL has lost lock. At this point,
the lock criteria is tightened and the lock detect process is repeated.
The alternate count sequences prevent false lock detects due to
frequency aliasing while the PLL tries to lock. Alternating between tight
and relaxed lock criteria prevents the lock detect function from randomly
toggling between locked and non-locked status due to phase
sensitivities.
non-locked conditions.
In external clock mode, the PLL is disabled and cannot lock.
AND COMPARE
COUNT N
Freescale Semiconductor, Inc.
For More Information On This Product,
Figure 11-6. Lock Detect Sequence
REFERENCE COUNT
FEEDBACK COUNT
Go to: www.freescale.com
Figure 11-6
IN SAME COUNT/COMPARE SEQUENCE
Clock Module
CONDITION AND NOTIFY
FEEDBACK COUNT = N
REFERENCE COUNT =
AND NOTIFY SYSTEM OF LOSS
SET RELAXED LOCK
LOCK DETECTED.
SYSTEM OF LOCK
SET TIGHT LOCK CRITERIA
LOSS OF LOCK DETECTED
OF LOCK CONDITION
CONDITION
shows the sequence for detecting locked and
MMC2114 • MMC2113 • MMC2112 — Rev. 1.0
REFERENCE COUNT =
FEEDBACK COUNT = N + K
IN SAME COUNT/COMPARE SEQUENCE
AND COMPARE NUMBER
REFERENCE COUNT
OF FEEDBACK CYCLES
REFERENCE CYCLES
FEEDBACK COUNT
COUNT N + K
ELAPSED
MOTOROLA