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Re: STM32F030 custom board

Posted: Fri Feb 24, 2017 3:10 am
by ddrown
Update! I wrote two long things on my blog: https://blog.dan.drown.org/frequency-sy ... se-in-ntp/ + https://blog.dan.drown.org/temperature-compensation/

But some highlights:

Test system:

Image

Frequency vs temperature:

Image

Remaining error after removing the fit line from the previous graph:

Image

When the temperature goes down:

Image

My supply voltage goes up by 4mV:

Image

Re: STM32F030 custom board

Posted: Thu Mar 23, 2017 8:23 pm
by Bingo600
These are actually nice OCXO's
http://www.ebay.com/itm/NEW-10MHz-OCXO- ... 2308905189

DS
http://www.microcrystal.com/images/_PDF ... r/OCXO.pdf

Uses less than 80ma@20c , 300ma@startup (10 sec) , they're 5v supplied


This one seems to have somewhat same specs
http://www.ebay.com/itm/10MHz-OCXO-DIP- ... 2868381695
http://www.golledge.com/pdf/products/ocxos/scocxovt.pdf

/Bingo

Re: STM32F030 custom board

Posted: Thu Mar 23, 2017 8:50 pm
by ddrown
Bingo600 wrote:These are actually nice OCXO's
http://www.ebay.com/itm/NEW-10MHz-OCXO- ... 2308905189

DS
http://www.microcrystal.com/images/_PDF ... r/OCXO.pdf

Uses less than 80ma@20c , 300ma@startup (10 sec) , they're 5v supplied


This one seems to have somewhat same specs
http://www.ebay.com/itm/10MHz-OCXO-DIP- ... 2868381695
http://www.golledge.com/pdf/products/ocxos/scocxovt.pdf

/Bingo


Thanks, those are good specs. 150ppb stability over -20C to 70C is at least 16x better than what I'm using now.

However, I think I'm going to stick with the TCXOs for now. I'm pretty happy with the results I got by fitting the frequency vs Temperature data:

Image

After measuring the frequency vs temperature curve of these two boards, I increased my 2.5ppm part's stability to 0.036ppm.

more at: https://blog.dan.drown.org/temperature- ... on-part-2/