Datasheet

LPC11E6X All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet Rev. 1.2 — 21 May 2014 35 of 89
NXP Semiconductors
LPC11E6x
32-bit ARM Cortex-M0+ microcontroller
8.24.3 Integrated oscillators
The LPC11E6x include the following independent oscillators: the system oscillator, the
Internal RC oscillator (IRC), the watchdog oscillator, and the 32 kHz RTC oscillator. Each
oscillator can be used for more than one purpose as required in a particular application.
Following reset, the LPC11E6x operates from the internal RC oscillator until software
switches to a different clock source. The IRC allows the system to operate without any
external crystal and the bootloader code to operate at a known frequency.
See Figure 10
for an overview of the LPC11E6x clock generation.
8.24.3.1 Internal RC oscillator
The IRC can be used as the clock source for the WDT or as the clock that drives the
system PLL and then the CPU. The nominal IRC frequency is 12 MHz.
Upon power-up, any chip reset, or wake-up from Deep power-down mode, the LPC11E6x
use the IRC as the clock source. Software can later switch to one of the other available
clock sources.
8.24.3.2 System oscillator
The system oscillator can be used as the clock source for the CPU, with or without using
the PLL.
Fig 11. Power distribution
REAL-TIME CLOCK
BACKUP REGISTERS
WAKE-UP
CONTROL
REGULATOR
32 kHz
OSCILLATOR
ALWAYS-ON/RTC POWER DOMAIN
MAIN POWER DOMAIN
RTCXIN
VBAT
VDD
RTCXOUT
VDD
VSS
to memories,
peripherals,
oscillators,
PLL
to core
to I/O pads
ADC
TEMP SENSE
ADC POWER DOMAIN
VDDA
VSSA
LPC11E6x
ULTRA LOW-POWER
REGULATOR
WAKEUP
aaa-011054