Datasheet

LPC111X All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet Rev. 9.2 — 26 March 2014 53 of 127
NXP Semiconductors
LPC1110/11/12/13/14/15
32-bit ARM Cortex-M0 microcontroller
Following reset, the LPC1110/11/12/13/14/15 will operate from the Internal RC oscillator
until switched by software. This allows systems to operate without any external crystal and
the bootloader code to operate at a known frequency.
See Figure 16
for an overview of the LPC1110/11/12/13/14/15 clock generation.
7.16.1.1 Internal RC oscillator
The IRC may be used as the clock source for the WDT, and/or as the clock that drives the
PLL and subsequently the CPU. The nominal IRC frequency is 12 MHz. The IRC is
trimmed to 1 % accuracy over the entire voltage and temperature range.
Upon power-up or any chip reset, the LPC1110/11/12/13/14/15 use the IRC as the clock
source. Software may later switch to one of the other available clock sources.
7.16.1.2 System oscillator
The system oscillator can be used as the clock source for the CPU, with or without using
the PLL.
Fig 16. LPC1110/11/12/13/14/15 clock generation block diagram
SYSTEM PLL
IRC oscillator
system oscillator
watchdog oscillator
IRC oscillator
watchdog oscillator
MAINCLKSEL
(main clock select)
SYSPLLCLKSEL
(system PLL clock select)
SYSTEM CLOCK
DIVIDER
AHB clock 0
(system)
SYSAHBCLKCTRL[1:18]
(AHB clock enable)
AHB clocks 1 to 18
(memories
and peripherals)
SPI0 PERIPHERAL
CLOCK DIVIDER
SPI0
SPI1 PERIPHERAL
CLOCK DIVIDER
SPI1
UART PERIPHERAL
CLOCK DIVIDER
UART
WDT CLOCK
DIVIDER
WDT
WDTUEN
(WDT clock update enable)
watchdog oscillator
IRC oscillator
system oscillator
CLKOUT PIN CLOCK
DIVIDER
CLKOUT pin
CLKOUTUEN
(CLKOUT update enable)
002aae514
main clock
system clock
IRC oscillator
18