Hello,

I am using DS1643/48T08 for RTC and memory.
As NVRAM is not necessary for my application, I sourced Philips 8563. Works well. But the crytal freq tends to shift because of external capacitors (parasitic). Reference to determine the drift was again DS1643. I believe with high Q crystal resonance freq should not be so susceptible to parasitic caps.

Variations are till 32.773 KHz.

Any observations?

Regards