Dear Forum Members,
I need your help regarding Real Time Clock chips.
We are having an MCS51 family based product, which has a Real Time Clock.
I have tried two RTC chips, but none of them worked 100% perfect. I have tried PCF8583 (now discontinued by Philips and they informed us to use PCF8563. We got this info directly from Philips offices in Mumbai, India.) and PCF8563. Both the chips had the problem of RTC jump, or IIC failures, and had a lack of support from Philips (since we do not buy these chips in large quantity). Hence we decided to use RTC from Dallas (Maxim). We tried DS1904, and it worked OK for our application. But it is giving a serious problem, that, it is giving an inaccuracy of about 2 minutes fast per day, i.e. about 5 seconds fast per hour. Now this DS1904, has got a crystal, battery inbuilt.
Does anybody know how to solve this problem, or any other RTC Chip, which gives a better performance?
I have tested for time accuracy of various DS1904, and most of them gave various readings.
Our product is meant to be installed at places, where the ambient temperature, may change from 10 Deg. C, to 50 Deg. C. It may also be installed in direct sunlight (although we insist NOT to install in direct sunlight, but for some odd installations we are forced to install it in direct sunlight.
Awaiting your valued suggestions.

With warm regards,
From Mr. Kiran V. Sutar