CDCM61001 input crystal frequency

Shaun Caraway

Other Parts Discussed in Thread: CDCM61001

I want to use the CDCM61001 to generate a 66.67MHz LVDS clock signal. From using the equation on page 2 and table 3 "Table 3. Generic Configuration" on page 11. I see that I will need an input crystal with a frequency of 26.664MHz. Will a crystal with a frequency of 26.65MHz be sufficient or will I need to find a crystal that exactly matches the calculated value?

over 11 years ago

0 Arvind Sridhar over 11 years ago

TI__Mastermind 24205 points

Hi Caraway,

If the target output frequency is 66+2/3 MHz, the required reference clock is 26+2/3 MHz. If you have difficultly finding the exact crystal frequeny, you could try reference oscillator from digikey

http://www.digikey.com/product-search/en?pv183=6357&pv139=2598&pv139=3150&pv139=3303&pv139=3254&pv139=2914&FV=fff4000d%2Cfff8016e&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25

If you used a 26.65 MHz reference crystal (common), there will be a ppm error on the output frequency = ((26+2/3) - 26.65) / (26+2/3)*1000000 = 625 ppm

Regards

Arvind Sridhar

Clock & timing

Clock & timing forum

CDCM61001 input crystal frequency