Just use a DS1302 and a coin-cell battery.

Gabriel

-----Original Message-----
From: Hickman, Aaron <HickmanAB@MAIL.VMI.EDU>
To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
Date: Thursday, August 05, 1999 11:12 AM
Subject: battery backup for RTC needed


>To All,
>
>        I am looking for a simple battery backup solution for a project
>involving an RTC.  I would like to keep the clock running should power,
normally
>derived from an AC to DC converter, be interrupted.  I have no experience
in
>battery charging/backup designs.  Could someone point me in the right
direction,
>preferably towards a design available on the internet?
>
>Sincerely,
>
>Aaron Hickman