Lpc2000

Hello Dave,

> 
> I'm using a LPC2214 & have connected the XCLK pin to a single input of 
> another IC which needs to be sync'd with the CPU. I'm driving XCLK at 
> 59MHz and I'm seeing an almost sinusoidal waveform ~2v pk-pk going 
> between 0.5v & 2.5v which is very marginal. Is the XCLK pin capable of 
> driving a 10pF input located 15mm away from the XCLK pin ?
> 

10pF represents around 270ohms at that frequency. I am not familiar
with the LPC2214 but that doesn't seem like much of a load for a uC.
Are you sure it's only 10pF?

Lift the pin of the other IC and look again. If still sinusoidal the
trace capacitance might be a bit high. If your scope probe is suspect
you could use a resistive divider into a 50ohm coax and hook that to a
fast scope (at least 1GHz) with the scope input terminated with
50ohms. The divider should have a ratio of 5-10, not more to avoid
stray capacitances that could otherwise foul up things.

If your trace is longer than an inch or two you may need a controlled
impedance trace and a terminator at the target IC.

Regards, Joerg

http://www.analogconsultants.com/