RTC's are always more accurate.
It all depends on the crystal or clock source used. If you drive the clock input of an 8051 with a surplus +/- 5 ppb ovenized oscillator it will be a lot
more accurate than a RTC using a +/- 50 ppm 32,768 Hz watch crystal. Of course, no one drives an 8051 with a $30 high precision oscillator.
In general, 32,768 Hz watch crystals have a much better accuracy and precision than the crystals usually used to form the oscillator circuit of a microcontroller.Posted on: December 08, 2008, 08:38:54 20:38 - Automerged
brijbhoomi, I took a brief look at the circuit. The crystal oscillator in the RTC may not be completely modeled. Consult the data sheet and try driving one of the inputs with a logic-level square wave input. Did you look at the online help for the model to determine the limitations?