I'm currently using a Maximum Integrated MAX7375 MEMS 8MHz oscillator (http://www.digikey.ca/product-detail/en/maxim-integrated/MAX7375AXR805-T/MAX7375AXR805-TCT-ND/4967873) as a clock source for a microcontroller project.
While doing some tests on the microcontroller, I noticed that the internal time of the microcontroller was going a little faster than the real world time. For example, when I would set an alarm on the microcontroller for 30 minutes, it would be go off after 29:44. When I would set it for 1 hour, it would go off at 59:28.
I then attempted another timing method within the microcontroller and had the same results. I decided that my 8MHz clock must be going a little faster than 8MHz. I then took the oscillator to the oscilloscope and was able to confirm that my clock was operating at 8.09MHz.
So my question: is this performance typical, or in range for this oscillator? I notice that the data sheet specs the oscillator as 8.00MHz, which seems to suggest that my oscillator is operating at the worst possible rate for its tolerance.
Furthermore, why exactly would this oscillator be performing so poorly? I thought MEMS oscillators were often considered superior than cap/crystal resonators? Thoughts?
Best Answer
The answer is behind the characteristics:
So, this part has a minimum frequency of 8 x 0.96 = 7.68MHz and a maximum frequency of 8 x 1.04 = 8.32MHz. You measured 8.09MHz which is in guaranteed range.