![NXP Semiconductors LPC43Sxx Скачать руководство пользователя страница 197](http://html1.mh-extra.com/html/nxp-semiconductors/lpc43sxx/lpc43sxx_user-manual_1721827197.webp)
UM10503
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2015. All rights reserved.
User manual
Rev. 2.1 — 10 December 2015
197 of 1441
NXP Semiconductors
UM10503
Chapter 13: LPC43xx/LPC43Sxx Clock Generation Unit (CGU)
13.7.4.1 Features
•
Input frequency: 14 kHz to 150 MHz. The input from an external crystal is limited to
25 MHz.
•
CCO frequency: 275 MHz to 550 MHz.
•
Output clock range: 4.3 MHz to 550 MHz.
•
Programmable dividers:
–
Pre-divider N (N, 1 to 2
8
)
–
Feedback-divider 2 x M (M, 1 to 2
15
)
–
Post-divider P x 2 (P, 1 to 2
5
).
•
Programmable bandwidth (integrating action, proportional action, high frequency
pole).
•
On-the-fly adjustment of the clock possible (dividers with handshake control).
•
Positive edge clocking.
•
Frequency limiter to avoid hang-up of the PLL.
•
Lock detector.
•
Power-down mode.
•
Free running mode
Remark:
Both PLL0 blocks are functionally identical. The PLL0 for audio applications
(PLL0 for audio) supports an additional fractional divider stage (see
).
13.7.4.2 PLL0 description
The block diagram of the PLL0 is shown in
. The clock input has to be fed to pin
clkin. Pin clkout is the PLL0 clock output. The analog part of the PLL consists of a Phase
Frequency Detector (PFD), filter and a Current Controlled Oscillator (CCO). The PFD has
two inputs, a reference input from the (divided) external clock and one input from the
divided CCO output clock. The PFD compares the phase/frequency of these input signals
and generates a control signal if they don’t match. This control signal is fed to a filter
which drives the CCO.