[time-nuts] Casio Watches 13 Year Drift in Seattle

[Mark Sims]

A friend of mine is the test engineer/clock guru for one of the major manufacturers of clock chips.   Rest assured that all watch makers know the usage profiles for their customers quite well and they do indeed tweak the chip to compensate for the typical profile.   If your usage pattern does not match that of the masses,  your accuracy can suffer.
Also,  you cant assume that all clock circuits will run faster or slower with rising/falling temperature changes.  Some circuits run faster with rising temperatures, others will run slower.
A very big concern in the clock chip world these days is getting the clock/crystal to start/run reliably with the ever decreasing power requirements of the customers.  A clock chip oscillator these days draws in the low nanoamp area,  and they can be very sensitive to things like electrical noise (beware of the dreaded stepper noise), board layout, IC process variations, etc.