[time-nuts] Glass Envelope Quartz Crystals
holrum at hotmail.com
Sun Feb 7 20:32:49 EST 2016
> The dynam al capacitance is a couple of fF, and thus R1 is between 10k to 80k depending on the size
A friend of mine has been fighting a 32 kHz clock problem on an ARM processor (used to wake up from periodic sleeps). In discussions with the CPU and crystal makers it looks like some of the modern tiny (2mm or less) clock crystals have a resistance in the 250K range. Load caps need to be in the 2-4 pF range. The oscillators are running in the nano-amp/watt region and can be VERY picky about what it takes to make them work reliably. Plus clock jitter tends to be in the mega-horrible range. And don't get him started about the wonders of 01005 sized SMT passives...
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