Datasheet

LPC1311_13_42_43 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2012. All rights reserved.
Product data sheet Rev. 5 — 6 June 2012 25 of 74
NXP Semiconductors
LPC1311/13/42/43
32-bit ARM Cortex-M3 microcontroller
7.18.1.1 Internal RC oscillator
The IRC may be used as the clock source for the WDT, and/or as the clock that drives the
system 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.
The USB clock is available on LPC1342/43 only. SSP1 is available on LPC1313FBD48/01 only.
Fig 7. LPC1311/13/42/43 clocking generation block diagram
SYSTEM PLL
IRC oscillator
system oscillator
system oscillator
watchdog oscillator
IRC oscillator
watchdog oscillator
USB PLL
MAINCLKSEL
(main clock select)
SYSPLLCLKSEL
(system PLL clock select)
USBPLLCLKSEL
(USB clock select)
SYSTEM CLOCK
DIVIDER
AHBCLKCTRL
(AHB clock enable)
AHB clock 0
(system)
AHB clock 1
(ROM)
AHB clock 16
(IOCONFIG)
AHBCLKCTRL
AHBCLKCTRL
SSP0/1 PERIPHERAL
CLOCK DIVIDER
SSP0/1
UART PERIPHERAL
CLOCK DIVIDER
UART
SYSTICK TIMER
CLOCK DIVIDER
WDT CLOCK
DIVIDER
SYSTICK
timer
ARM TRACE
CLOCK DIVIDER
ARM
trace clock
WDT
WDTUEN
(WDT clock update enable)
USB 48 MHz CLOCK
DIVIDER
USB
USBUEN
(USB clock update enable)
watchdog oscillator
IRC oscillator
system oscillator
CLKOUT PIN CLOCK
DIVIDER
CLKOUT pin
CLKOUTUEN
(CLKOUT update enable)
002aae859
main clock
system clock
IRC oscillator
AHB clocks
2 to 15
(memories
and peripherals)
14
2