×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Best Way To Generate 2 Clocks - 33 MHz & 64 MHz

Best Way To Generate 2 Clocks - 33 MHz & 64 MHz

Best Way To Generate 2 Clocks - 33 MHz & 64 MHz

(OP)
Hi,

Instead of using 2 separate oscillators, is there a way to generate both 33MHz and 64Mhz with 1 device?? The values don't divide evenly. Please let me know.

Thanks,

swb1  
 

RE: Best Way To Generate 2 Clocks - 33 MHz & 64 MHz

PLL

RE: Best Way To Generate 2 Clocks - 33 MHz & 64 MHz

(OP)
Do you have a part that you can suggest?? The PLLs that I have saw have even divides like 2, 4, 6, 8, 12.

Thanks,

swb1

RE: Best Way To Generate 2 Clocks - 33 MHz & 64 MHz

2 separate oscillators would probably be simpler. A PLL circuit will inevitably involve more components (since oscillators are often just one).

The PLL approach would be to divide the 64 MHz by two repeatedly (2^6) to make 1 MHz as the reference. The PLL oscillator would oscillate at 33 MHz, and a sample of that would be divided by 33 (a tiny bit tricky) and phase locked to the reference. Since it is a fixed frequency (?), the loop parameters should be simple to work out.

Sometimes designers will aim for twice the desired frequency and divided by two as the last step to precisely even-up the duty-cycle.
 

RE: Best Way To Generate 2 Clocks - 33 MHz & 64 MHz

Hmmm... Another option would be to generate 2112 (the LCM, not the Rush album) MHz and divide down. Probably too high to be practical.

 

RE: Best Way To Generate 2 Clocks - 33 MHz & 64 MHz

Generate 11 MHz and pass filter the second and third harmonic.

old field guy

RE: Best Way To Generate 2 Clocks - 33 MHz & 64 MHz

What's the 22MHz for?

 

RE: Best Way To Generate 2 Clocks - 33 MHz & 64 MHz

(OP)
Cypress makes a programmable clock generator (CY22381) that will seem to work.

swb1

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources