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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
42 of 808
NXP Semiconductors
UM10360
Chapter 4: LPC17xx Clocking and power control
6.2 PLL1 Control register (PLL1CON - 0x400F C0A0)
The PLL1CON register contains the bits that enable and connect PLL1. Enabling PLL1
allows it to attempt to lock to the current settings of the multiplier and divider values.
Connecting PLL1 causes the USB subsystem to run from the PLL1 output clock. Changes
to the PLL1CON register do not take effect until a correct PLL feed sequence has been
given (see
Fig 9.
PLL1 block diagram
CD
/2P
CLOCK
SYNCHRONIZATION
PD
CCLK
PLLC
PLOCK
F
OSC
PLLE
PHASE-
FREQUENCY
DETECTOR
bypass
MSEL[4:0]
CD
MSEL<4:0>
F
OUT
DIV-BY-M
CCO
F
CCO
0
0
PSEL[1:0]
direct
1
0
0
1
0
1
PD
PD