Si5351A Breakout Board Documentation

I appreciate all of the interest in the Si5351A Breakout Board that I have available on OSHPark. I apologize for not having this available sooner, but here is a GitHub repository which hosts the KiCad design files and a PDF of the Breakout Board schematic, which lists the part numbers for the reference oscillator and the output transformers so that you can order your own. Also the few passives on the board are size 0805.

This, along with either the avr-gcc library or the Arduino library, should get you going in generating all kinds of clocks and local oscillators. While this board seems to work fine in interfacing with the 5V Arduinos that I have, I worry that comms might be iffy, so I’m going to add simple MOSFET-based level conversion to the next iteration of this board. Keep an eye on the blog for further developments in this area.

15 thoughts on “Si5351A Breakout Board Documentation

  1. Hi !

    For the next revision, please consider using a longest length below 50mm (= 1.96 inch, not 1.97) to fit the metric standard of some PCB manufacturers.

    Tnx and 73 !

  2. Hi Larry,

    I’m not quite sure I understand the request. Are you saying that some PCB manufacturers won’t accept any length 50 mm or longer? That’s not a very big board! What size are you looking for?


  3. Hi Jason

    I meant that some manufacturers (ex SeeedStudio / FusionPCB) have a price for 50 x 50 mm, another one for 50 x 100, another one for 100 x 100. If one side is longer than 50 mm (even by 0.1mm), you have to pay for the 50 x 100 mm board (instead of 50 x 50).



  4. Larry,

    Oh, are you getting back from the vendor that the design is slightly larger than 50 mm? I drew it in CAD to be 50 mm exactly, but perhaps there is a bit of a rounding error in the Gerber output. I can see about backing it off a few tenths of a millimeter.


  5. Jason,
    Can you suggest a sub for the Mini Circuits transformers? They require 20 piece min order. RFMD has a similar part.
    Jim – WB4HYY

  6. Hi Jim,

    Strictly from an electrical specification standpoint, the RFMD RFXF0013 would probably be a fairly suitable substitution (as long as you didn’t mind the lower frequency cutoff of 5 MHz). But the problem is that its footprint is significantly smaller than the TC1-6X+, so I don’t think that will work. Unfortunately, I don’t have the time to search for a replacement, but any reasonable broadband 1:1 transformer that will fit the footprint should be find. Perhaps you could even make one with a small binocular ferrite core.

    I’m sorry that the TC1-6X+ is inconvenient to buy in small quantities. Once I get my hands on a larger quantity of them, perhaps I can resell them in smaller quantities to those who are interested.


  7. Jason,

    I broke down and bought the Mini Circuits baluns along with some parts for other projects on the long list. I have the board assembled and connected to a Arduino Mini running your example but not getting any output for some reason. The serial port is showing SYS_INIT and LOL bits =0 and LOS =1. My 5315A came from Digikey so I assume the I2C address of x60 is correct. SCA and SCL pullups in place and signals look good on scope. I would suspect my bad soldering but the fact status gets returned means. I will keep probing.


  8. Jason,

    Success! Was a bad soldering job on the crystal. Maybe at 62 years old I am past my SMD soldering prime!

    I took a look at all the code you wrote in the library and must say its very impressive. I had a EE student spend a summer trying to make a 5351 work and he finally gave up trying to put the complex math into embedded code.

    Now on to try and make it generate FSK for a beacon project.


  9. Hey Jim,

    Very happy to know that your breakout board is up and running!

    I know that the footprint for the crystal on that board is pretty small for hand soldering. I used the suggested footprint in the datasheet for that revision, but decided to up the size of the pads quite a bit in Rev B. It should be much, much easier to get a good solder connection on the Rev B board.

    I can’t take much of the credit for the basic tuning algorithm in the code, as that was taken from the Linux kernel driver library. You are right that it is difficult to figure out. The documentation is a bit inscrutable and riddled with errors. I didn’t have a handle on how to do it in an embedded device until I saw that kernel code.

    It should be very easy to do a FSK beacon at this point. Please let us know when you get it working; I would love to see it!


Leave a Reply