[time-nuts] Si5351B

[Achim Gratz]

D. Jeff Dionne writes:
> On Feb 4, 2019, at 14:25, Achim Gratz <Stromeko-i47jiTeKxPI at public.gmane.org> wrote:
>
>> The Si5351 needs something between 25MHz and 27MHz as reference.  
>
> That isn't true.

Well, that's what the datasheet says.  :-)

> Even the B version works just fine with a OCXO input
> directly.  See my thread here:
> https://www.silabs.com/community/timing/forum.topic.html/si5351_msop10_packag-wocK

I suspected as much, I just wasn't sure how much leeway I had.  The
discussions I've read so far didn't cover that aspect specifically, so
thanks for giving me this link.

> The problem is the Silicon Labs software to calculate the registers
> flags an error, so you have to calculate them yourself.  This is not
> hard, there are programs and references on the web.

I wasn't planning on using their software, so that hurdle is out of the
way also.

>> I'm currently mulling if it's worth the risk going slightly lower, as
>> there are nice and cheap OCXO at 24.576MHz I could actually buy,
>> whereas my options at the actual range boil down to just a single
>> unit (I've only looked at two distributors, though).
>
> That will certainly derisk the design, but it will not solve the
> SiLabs software issue.  Having used this approach, I can say my
> sampling of Si5351 chips with 10MHz OCXO all worked just fine, so
> 24.576MHz certainly will.

OK, so I have probably even more options to chose from.  That's very
welcome news.

Thanks for your input!


Regards,
Achim.
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