Lpc2000

A fairly low-value resistor is sometimes placed in series with a 32 
KHz crystal to reduce the drive level. Most 32 KHz crystals don't 
require (and some can't tolerate) as much drive as higher frequency 
crystals usually do. If the processor has a configuration setting to 
reduce the level (like the PIC micros do), the series resistor is 
usually omitted.


Regards, Bob


--- In lpc2000@yahoogroups.com, "dharmaBum" <dharmabum@y...> wrote:
> 
> If anyone has successfully used a 32 KHz crystal with the LPC2138, 
> please explain how to connect the crystal.  
> 
> I saw an example on the Keil eval board where a resistor was 
> connected in series with the crystal.  I don't understand how that 
> circuit operates.
> 
> Generally, a 10M or other large resistor is connected in parallel 
> with a crystal in order to bias the oscillator buffer (inside the 
> uP) into its linear region.
> 
> Has Philips released a more complete data sheet or user manual?
> 
> Thanks for the help,
> Wayne Radochonski