Lpc2000

At 02:03 PM 8/26/04 +0000, you wrote:
>Just a simple question about the cristal. I know that this MCU (as
>some PICs) has internal PLL. The question is, which is te range of
>External Cristal OSC, and then between what ranges I have to set the
>Internal PLL. I read somewhere, don't remember where, that the
>external cristal should be between 1MHz and 25Mhz, and in the PLL
>Calculator program, there's a maximun of 60Mhz for the clock.
>Which is the more recomendable selection, and which one gives more
>performance (higher Bus Clock, Higher MCU clock...and so on).
>Thanks for the patience...
>Ezequiel

 From the user manual (which according to post by Philips needs updated in 
this area):

• On-chip crystal oscillator with an operating range of 10 MHz to 25 MHz.
The PLL accepts an input clock frequency in the range of 10 MHz to 25 MHz.

 From Rev 4 of the data sheet

External Clock
fosc Oscillator frequency supplied by an external oscillator (signal 
generator)  1 - 50 MHz

External clock frequency supplied by an external crystal oscillator 1 - 30 MHz

External clock frequency if on-chip PLL is used 10 - 25 MHz

External clock frequency if ISP is used for initial code download 10 - 25 MHz

PLL can multiply up to 60MHz.  Bus characteristics (which are purely 
internal) are dealt with separate timing setups.  I suggest reading the 
user manual for a quick overview of how they work.

Robert


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