Lpc2000

I did not see any specification in the Datasheet on the input 
impedance of the Analog inputs. When I switch A/D channels, this 
impedance will determine how long the sampling time should be before 
the conversion can start. When in Burst mode, there is no mention on 
the sampling time at all. 

Can I assume that the 11 clocks already take care of this ?

Any ideas ? 

Thanks

Lei