lpc1759 NXP Semiconductors, lpc1759 Datasheet - Page 29

• Manufacturer Part Number: lpc1759
• Description: Lpc17xx Device Highlight
• Manufacturer: NXP Semiconductors

NXP Semiconductors
LPC1759_58_56_54_52_51_4
Product data sheet
Fig 4.
LPC1759/58/56/54/52/51 clocking generation block diagram
7.29.1.1 Internal RC oscillator
7.29.1.2 Main oscillator
7.29.1.3 RTC oscillator
LPC17xx
OSCILLATOR
OSCILLATOR
OSCILLATOR
INTERNAL
MAIN
RTC
RC
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 LPC1759/58/56/54/52/51 use the IRC as the clock
source. Software may later switch to one of the other available clock sources.
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
The RTC oscillator can be used as the clock source for the RTC block, the main PLL,
and/or the CPU.
32 kHz
(CLKSRCSEL)
system
select
rtclk = 1Hz
clock
pclk
All information provided in this document is subject to legal disclaimers.
Section 7.29.2
WDT
WATCHDOG
MAIN PLL
USB PLL
TIMER
REAL-TIME
Rev. 04.02 — 1 April 2010
CLOCK
main PLL enable
for additional information.
pllclk
LPC1759/58/56/54/52/51
PERIPHERAL
GENERATOR
CLOCK
CPU clock config
USB clock config
(USBCLKCFG)
(CCLKCFG)
DIVIDER
DIVIDER
CLOCK
CLOCK
USB
CPU
32-bit ARM Cortex-M3 microcontroller
CCLK/4
CCLK/2
CCLK
CCLK/8
CCLK/6
cclk
USB PLL enable
CORTEX-M3
(48 MHz)
ETHERNET
usbclk
BLOCK
ARM
GPIO
NVIC
DMA
USB BLOCK
APB peripherals
© NXP B.V. 2010. All rights reserved.
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