32Mhz Oscillator for Papilio pro


Narayanan

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Here is a part number at Digikey:

535-10082-1-ND

 

I can't vouch for it since I have never used it though. When I designed the Papilio I was also manufacturing them all myself which is why we ended up with a 32Mhz clock. I knew I wanted something slower then 50Mhz, I wanted to stack the cards in our favor by avoiding any potential high speed signal integrity issues by going with something less then 50Mhz... With the DCM we can generate anything we need and so I scoured ebay for wholesale oscillator lots less then 50Mhz. I got a great deal on several reels of 32Mhz oscillators that made them less then .05 each. So I've always had an over abundant supply of 32Mhz oscillators and have never purchased one from digikey...

 

Jack.

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...With the DCM we can generate anything we need and so I scoured ebay for wholesale oscillator lots less then 50Mhz. I got a great deal on several reels of 32Mhz oscillators that made them less then .05 each. So I've always had an over abundant supply of 32Mhz oscillators and have never purchased one from digikey...

 

Jack.

 

as we are on this topic, let me ask a suggestion; i'm planning to set up some design related to DVB transport stream  (filtering, remapping, PCR restamping). the standard clock for DVB is usually 27MHz. 

 

do you think i can just swap the actual 32MHz part with a 27Mhz and be pretty done with it?

 

i mean if you know there are "critical loop" in some binary code in the micro that could be upset if i change the reference clock.

 

finally, do you know the digikey part number that's compliant with the actual form factor?

 

the swap should be  a pretty quick job of a rework station, right?

 

bests

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I agree with alex, I would try to generate a 27Mhz clock with the DCM first. But, yes, it would be a very simple rework to swap the 32Mhz clock with a 27Mhz clock. I've done it with a soldering iron and some flux several times, or a hot air station is even better.

 

If you do change the oscillator none of the existing Papilio projects will work without modification. Not sure if that is a concern or not...

 

The best way to find the correct 27Mhz oscillator is to look at the part number I gave earlier on Digikey. Its a pretty standard 7mm x 5mm size so get a 27Mhz oscillator that is the same, and then make sure the pinout is the same.

 

Jack

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Even with a 27 MHz oscillator you would still want to use a DCM to clean up the clock signal.

 

thanks for all the advices. it looks like simpler then i expected! :-)

 

i'll try surely the DCM with 32->27 synthesis.. i checked coregen and indeed it spits out a "perfect" 27MHz without rounding in the wizard.

 

Andrea

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