LPC5411x
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© NXP Semiconductors N.V. 2018. All rights reserved.
Product data sheet
Rev. 2.1 — 9 May 2018
28 of 105
NXP Semiconductors
LPC5411x
32-bit ARM Cortex-M4/M0+ microcontroller
7.13.1.3
Clock input
An external square-wave clock source (up to 25 MHz) can be supplied on the digital I/O
pin CLKIN.
7.13.1.4
RTC Oscillator
An external RTC (32.768 kHz) can be used to create the main clock when the PLL input or
output is selected as the clock source to the main clock.
7.13.1.5
System PLL
The system PLL allows CPU operation up to the maximum CPU rate without the need for
a high-frequency external clock. The system PLL can run from the internal FRO 12 MHz
output, the external clock input CLKIN, or the RTC oscillator.
The system PLL accepts an input clock frequency in the range of 32 kHz to 25 MHz. The
input frequency is multiplied up to a high frequency with a Current Controlled Oscillator
(CCO) The PLL can be enabled or disabled by software.
7.13.2 Clock Generation
The system control block facilitates the clock generation. Many clocking variations are
possible.
gives an overview of the potential clock options.