UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
133 of 1269
NXP Semiconductors
UM10503
Chapter 11: LPC43xx Clock Generation Unit (CGU)
(2)
Non-integer mode
In this mode the post-divider is enabled and the feedback divider is set to run directly on
the CCO clock, which gives the following frequency dividers:
(3)
(4)
Direct mode
In this mode, the post-divider is disabled and the CCO clock is sent directly to the output,
leading to the following frequency equation:
(5)
Power-down mode
In this mode, the internal current reference will be turned off, the oscillator and the
phase-frequency detector will be stopped and the dividers will enter a reset state. While in
Power-down mode, the lock output will be low, to indicate that the PLL is not in lock. When
the Power-down mode is terminated, the PLL will resume its normal operation and will
make the lock signal high once it has regained lock on the input clock.
FCCO
2
P
FCLKOUT
2
P
M
FCLKIN
N
----------------------
=
=
FCLKOUT
FCCO
2
P
-----------------
M
2
P
------------
FCLKIN
N
----------------------
=
=
FCCO
M
FCLKIN
N
----------------------
=
FCLKOUT
FCCO
M
FCLKIN
N
----------------------
=
=