Lpc2000

stephan2148 wrote:

>Hi,
>Does anyone know if the RTC on the LPC2148 will still hold date/time
>if it has a separate lithium battery and crystal and the micro has
>lost power? I was hoping to powerdown totally and still have the RTC
>active.
>  
>

I'm doing this with the LPC2138.  You have to design the battery ciruit 
using two diodes and a resistor.  The diodes will switch the RTC supply 
over to battery / main supply.  The resistor limits current to the 
battery when the main power is up and will trickle charge (top off) the 
battery.

Contact me directly if you want the circuit.

TomW

-- 
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net, http://cyberiansoftware.com
"Windows? No thanks, I have work to do..."
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