Datasheet
LPC1315_16_17_45_46_47 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2012. All rights reserved.
Product data sheet Rev. 3 — 20 September 2012 32 of 77
NXP Semiconductors
LPC1315/16/17/45/46/47
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 divider is available on parts LPC1345/46/47 only.
Fig 9. LPC1315/16/17/45/46/47 clocking generation block diagram
system oscillator
watchdog oscillator
IRC oscillator
USB PLL
USBPLLCLKSEL
(USB clock select)
SYSTEM CLOCK
DIVIDER
SYSAHBCLKCTRLn
(AHB clock enable)
CPU, system control,
PMU
memories,
peripheral clocks
SSP0 PERIPHERAL
CLOCK DIVIDER
SSP0
SSP1 PERIPHERAL
CLOCK DIVIDER
SSP1
USART PERIPHERAL
CLOCK DIVIDER
UART
WDT
WDCLKSEL
(WDT clock select)
CLKOUTSEL
(CLKOUT clock select)
USB 48 MHz CLOCK
DIVIDER
USB
watchdog oscillator
IRC oscillator
system oscillator
USBCLKSEL
(USB clock select)
CLKOUT PIN CLOCK
DIVIDER
CLKOUT pin
002aag563
system clock
SYSTEM PLL
IRC oscillator
system oscillator
watchdog oscillator
MAINCLKSEL
(main clock select)
SYSPLLCLKSEL
(system PLL clock select)
main clock
IRC oscillator
n