Lpc2000

Hello Slawcus,

Philips has not conducted test(s) that would exactly match what you 
have described in the post, however if proper PLL setup & connect 
scheme are applied, we expect no problems. As long as the transition 
from one clock to another is kept glitch-free on the X1, and all side 
effects are taken in consideration prior to the design (i.e. impact 
on all of the on-chip peripherals), you are safe.

Regards,

Philips Apps Team



--- In lpc2000@yahoogroups.com, "slawcus" <slawcus@y...> wrote:
> I haven't noticed this in datasheet:
> 
> Can I drive X1 with low speed external clock without PLL, then 
change
> X1 frequency on the fly and after that use PLL?
> 
> Example: PDIUSBD12 CLKOUT - default is 4MHz (I'm aware of voltage
> limitation at X1 of LPC device). 
> LPC2106 X1 is driven by this 4MHz, during PDIUSBD12 setup change
> CLKOUT to the higher value > 10MHz. Turn on the PLL, continoue with
> normal operation. PDIUSBD12 CLKOUT change should be without glitches
> and frequency is not changed with USB reset (according to 
datasheet). 
> 
> Is this possible?
> 
> 
> 
> 
> --- In lpc2000@yahoogroups.com, "philips_apps" <philips_apps@y...> 
wrote:
> > "Crystal Oscillator" section in the "System Control Block" 
chapter of 
> > the LPC2114/2124/2212/2214 and LPC2119/2129/2194/2292/2294 User 
> > Manuals covers input frequency range topics.
> > 
> > If on-chip PLL system or boot-loader is used, input clock 
frequency 
> > is limited to exclusive range of 10 MHz to 25 Mhz. 
> > 
> > These restrictions are imposed by the design of the PLL 
circuitary. 
> > Since all Philips LPC2000 parts have the same PLL module, above 
> > requirements exist in the case of LPC2104/5/6 parts, too.
> > 
> > Regards,
> > 
> > Philips Apps Team
> > 
> > 
> > 
> > --- In lpc2000@yahoogroups.com, "tphatrapornnant" <tp35@l...> 
wrote:
> > > 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