LPC1767 View Datasheet(PDF) - NXP Semiconductors.
Part Name
Description
MFG CO.
'LPC1767' PDF : 79 Pages View PDF
NXP Semiconductors
LPC1769/68/67/66/65/64/63
32-bit ARM Cortex-M3 microcontroller
See Figure 5 for an overview of the LPC17xx clock generation.
LPC17xx
MAIN
OSCILLATOR
INTERNAL
RC
OSCILLATOR
system
clock
select
(CLKSRCSEL)
USB PLL
MAIN PLL
pllclk
main PLL enable
USB
CLOCK
DIVIDER
usbclk
(48 MHz)
USB BLOCK
USB clock config USB PLL enable
(USBCLKCFG)
CPU
cclk
CLOCK
DIVIDER
CPU clock config
(CCLKCFG)
ARM
CORTEX-M3
ETHERNET
BLOCK
WATCHDOG
TIMER
DMA
GPIO
NVIC
32 kHz
RTC
OSCILLATOR
pclkWDT
rtclk = 1Hz
REAL-TIME
CLOCK
PERIPHERAL
CLOCK
GENERATOR
CCLK/8
CCLK/6
CCLK/4
CCLK/2
CCLK
APB peripherals
Fig 5. LPC17xx clocking generation block diagram
002aad947
7.29.1.1 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 4 MHz. The IRC is
trimmed to 1 % accuracy over the entire voltage and temperature range.
Upon power-up or any chip reset, the LPC17xx use the IRC as the clock source. Software
may later switch to one of the other available clock sources.
7.29.1.2 Main oscillator
The main oscillator can be used as the clock source for the CPU, with or without using the
PLL. The main oscillator also provides the clock source for the dedicated USB PLL.
The main oscillator operates at frequencies of 1 MHz to 25 MHz. This frequency can be
boosted to a higher frequency, up to the maximum CPU operating frequency, by the main
PLL. The clock selected as the PLL input is PLLCLKIN. The ARM processor clock
frequency is referred to as CCLK elsewhere in this document. The frequencies of
PLLCLKIN and CCLK are the same value unless the PLL is active and connected. The
clock frequency for each peripheral can be selected individually and is referred to as
PCLK. Refer to Section 7.29.2 for additional information.
7.29.1.3 RTC oscillator
The RTC oscillator can be used as the clock source for the RTC block, the main PLL,
and/or the CPU.
LPC1769_68_67_66_65_64_63
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 7 — 5 April 2011
© NXP B.V. 2011. All rights reserved.
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