>
> The part specifies B2 capacitance for the 50Mhz crystal, and a B2F for the
> 25Mhz I need.  Both are from the same company and have the same data
> sheet.
> Any help?  What is the B for?  Does the two mean I need twice the cap. of
> the crystals value?



The part number mouser calls out dosen't match the system used in the
ordering options in the data sheet.
You can always call them and ask..
I'd expect to see a part number like: AB-50.000-18-R15-B-2-X-F
There's a note at the bottom that says "left blank if standard",  but I
don't see how they show you what's "standard" here.
I'd call abracon in the morning and ask.

Now.. The load capacitance number is not the value of the caps to use.
The two caps are in series from the crystal's point of view.
Basically, double that, and subtract 5 pF (as a first guess) for parasitic
capacitance in the circuit.
That gives you 31pF and the closest value without going over would be 27pF.
Try that, check operating frequency and oscillation margin, and then adjust
if you need to.
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