Dear Ahmed,
You may get a charger ckt from National Semiconductor Data sheet for LM350. I build this ckt and now it is up & running. Also you get a battery overflow indicator therein. If you go through that ckt, you will note that there is no mechanism to prevent BATT being discharging into the IC when ther is a mains power failer. So what I did was, I put a doide (IN5408) to stop this. However, with this alternative, there is a little voltage drop but negligible.