[51] Time in rtc being slow....

[Azzy anxious]

Hi
expert I want your help regarding my rtc project,actually i hav worked on DS1307 rtc and able to set time . But My problem is that its nt working properly as time slow downs while comparing wd real time .

Sometimes its working fine bt after some days or week it again slow downs..so can you help me as i can solv ma problem

:shock::shock::shock:

 

[techgreed]

The time slows down because the xtal might not be oscillating at the intended 32.768KHz. Check the effective load capacitance which appears across the crystal and see whether it matches with the crystal load capacitance.
If you RTC has a clkout option, measure the oscillating frequency through it.

 

[Azzy anxious]

How to check effective load capacitance ..................

 

[horace1]

the DS1307 will drift over time in particular with temperature variations - have a look at
https://www.maximintegrated.com/en/app-notes/index.mvp/id/58

there are temperature compensated RTCs, e.g. the DS3231
**broken link removed**

even then if the system is connected to the internet I would synchronize the time regularly