Clock sources

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YahooArchive
Posts: 1463
Joined: Fri Oct 19, 2012 5:11 am

Clock sources

Post by YahooArchive » Mon Feb 11, 2013 2:16 pm

>from the help line
>I have several of your Armite and PRO+ boards and I was wondering about the
clocking scheme. It looks like a ceramic resonator that is connected to the
clock port pins on the LPS2103. What frequency is the basic oscillator frequency
fed to the PLL. Is the the frequency from which all of the others are derived?
What is the clocking scheme on the LPC1756 based PRO+?

The LPC2103/06 boards use a 20 MHz ceramic resonator. The internal PLL
multiplies this to 60 MHz for the CPU clock.

The LPC175x boards use the IRC, the internal tuned RC oscillator which is
running at 4 MHz +/1 1%. The internal PLL multiplies this to 100 MHz.

For LPC11xx and LPC177x boards the IRS is running at 12 MHz. These use the PLL
to run at 48 or 96 MHz respectively.

Peripherals are running at 1/4 the CPU clock

In the LPC17xx and LPC11xx and some LPC21xx boards there are provisions for an
external crystal.



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