Morning Chaps,

Just a quick question about the dsPIC30F (2010) oscillator/PLL if I may.
Reading the datasheet (DS70118G), the table on page 122 says that the range of
inputs for external clocks (with PLL enabled) is 0-40MHz, so long as the
maximum final frequency of 120MHz is abided by.  My thinking was to inject a
15MHz input and use the 8x PLL to obtain 120MHz - ideally I'd like to use a
7.5MHz crystal with OSC1/2 and 16x PLL, but I can't find any place that sells
that frequency quartz.

HOWEVER, on pages 156 and 157, there are two tables that list the minimum and
maximum ranges for the PLL inputs as 4-10MHz; with a 10MHz clock you would
either end up with 160MHz (x16 PLL - and exceeding specs), or 80MHz (x8 PLL -
but only 2/3 of the maximum possible).

My question is - which table should I believe ?  Am I missing something, or is
this a contradiction in the datasheet ?  My gut feeling is to take the most
conservative of the figures - ie. don't inject more than 10MHz and expect the
PLL to like it.

And a second question would be - where can I get 7.5MHz crystals from in the
UK in small quantities (ie. 10) and at a reasonable price ?  I've tried
Farnell, RS, Rapid, Digikey, eBay and Quarndon but can't see any; I can pick
up 7.3728MHz ones easily, but you lose over 0.5 MIPS with those.  Not likely
to be a problem in my case I dare say, but still...

Cheers,

Pete Restall
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist