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Lpc2000

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Re: injecting an external 4 MHz clk into LPC2000, and using PLL - anyone done similar ?

2004-05-10 by tphatrapornnant

Hi,

As I remember, I used to try 2.0 MHz crystal oscilator but it seemed 
PLL can't work at lower than 10MHz. I have just tested by changing 
OSC from now 10 MHz to 2 MHz with 6 time multiplier. The 1 ms 
interrupt timer changed to 1.8 ms, it should be 5 ms. So, I afraid it 
doesn't work at 4 MHz.    

Teera.

--- In lpc2000@yahoogroups.com, "microbit" <microbit@c...> wrote:
> Hi All,
> 
> This might have come up before I think, but I can't seem to
> readily find it in my LPC2000 folder.
> 
> Has anyone ever tried supplying LPC2000 with an external 4 MHz
> clock signal, to be used with PLL at higher clock rates ?
> 
> Since it's a full swing Ext signal, I don't see any limitations, 
other
> than the osc buffer ckty, which surely should handle that.
> I'm thinking of multiplying up to 64 MHz cclk.. a tad too high.
> And 8 X = 32 MHz is too low.
> This is for LPC2119/29.
> Space is critical and I need to save an SMT Xtal real estate wise.
> 
> -- Kris

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