Lpc2000

In some place in the datasheet, the external xtal is specified as 10 
to 25MHz. There might be problems trying to get the PLL running 
properly off a 4MHz clock.

If you need a 4MHz clock for some other part of your board then 
perhaps you can generate this out of the LPC2119.


--- 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