So, I happen to have a full low-volume SMD assembly line here... for our
own products (although I did have similar thoughts to John about spinning a
couple of carrier boards for these type of parts but designed so they are
suitable for assembly on our line).
Our take on QFN's is that they're not a
I used to do SMTIf the solder paste does not absorb moisture when
stored it should be OK
People have had success with an iron frying pan on the stove .
I have used a hot air paint stripper gun with a metal funnel to re flow the
paste.
There cheap SMT re work stations on Alibaba now <$100
O
On 1/25/18 7:17 PM, Joseph Gwinn wrote:
On Thu, 25 Jan 2018 21:13:44 -0500, time-nuts-requ...@febo.com wrote:
Message: 2
Date: Thu, 25 Jan 2018 16:16:59 -0500
From: John Ackermann N8UR
To: time-nuts@febo.com
Subject: Re: [time-nuts] Slightly OT: interest in a four-output,
ultra-low jit
On Thu, 25 Jan 2018 21:13:44 -0500, time-nuts-requ...@febo.com wrote:
>
> Message: 2
> Date: Thu, 25 Jan 2018 16:16:59 -0500
> From: John Ackermann N8UR
> To: time-nuts@febo.com
> Subject: Re: [time-nuts] Slightly OT: interest in a four-output,
> ultra-low jitter, synthesizer block?
> Messa
I'm using a toaster oven I got from Walmart. It said it was 1500 watts on the
box, but is actually 1800 watts. It has two sets if heating elements. I
didn't insulate it at all and am only using one set of elements... 900 watts.
It hits my PbSn curve quite well. When the heat cycle is done,
On 1/25/18 3:28 PM, Ronald Held wrote:
Jim;
No need to order in the spring or fall anymore? Looking forward
to your data.
Ronald
you and me, and a bunch of other folks as well
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Can anybody comment on the toaster oven approach?
Is it practical for things like this? How much does a solder mask cost? How
much other stuff do I need? Does the solder paste need to be refrigerated
and other quirks like that?
What are the chances of a newbie getting a 44-QFN right on the
Jim;
No need to order in the spring or fall anymore? Looking forward
to your data.
Ronald
no kidding - there's a well known issue when MicroSemi took over
building CSACs from Symmetricom, these things (like many precision
timing widgets) have a "recipe" and it's easy to "lose the recipe"
Hi
> On Jan 25, 2018, at 5:47 PM, Ronald Held wrote:
>
> Nigel;
> Will read the PDF carefully.
> Ronald
>
>
> "if it runs for years (or even months)" sounds like an informed comment:-)
>
> When searching for some data recently I came across a report which
> might be relevant.
>
> "A
Nigel;
Will read the PDF carefully.
Ronald
"if it runs for years (or even months)" sounds like an informed comment:-)
When searching for some data recently I came across a report which
might be relevant.
"A Second Look at Chip Scale Atomic Clocks for Long Term Precision
Timing", writt
OSHSTENCILS.COM sells stencils by the square inch. They have 4 mil stainless, 3
mil Kapton, and 5 mil Kapton... I usually use the stainless ones.They also
sell syringes of solder paste. I keep mine in the fridge.I have year old
paste that works fine. There are now pastes that do not
I have had very good luck with a converted toaster oven, GC-10 solder
paste, and OSH Stencils metal stencils. Basically, if the temperature
profile is good and you have good solder paste application, decent
placement, good solder mask and correct pad sizes, everything solders
itself. I have built 7
On 1/25/18 1:18 PM, Hal Murray wrote:
lajeune...@mail.com said:
I'm sure you know the 1.8V supply regulators should not be fed from VDDA
(3.3V), but I'll mention it anyway.
usually, it's so that noise coupled back from the part doesn't back in
through the 1.8V.
If you have a (say) 5V suppl
Hi
You can mod toaster ovens, they work ok, EEVB has *lots* of info on that. When
you buy
your PCB you can get solder stencils at the same time. Bought as a package they
are in the
$10 or so range. Without buying the boards with them, I’m sure the price goes
up a bit. The
metal ones are a bit m
lajeune...@mail.com said:
> Any non-zero output impedance and the digital load changes enter back in as
> noise on what should be the quiet VDDA.
Thanks. I missed the "A" on the VDDA.
--
These are my opinions. I hate spam.
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j...@febo.com said:
> The challenge is that the chip is a 7x7 mm 44-QFN package and really wants
> to be put on a six-layer circuit board. That's doable, but challenging,
> for home assembly.
Can anybody comment on the toaster oven approach?
Is it practical for things like this? How much do
On Thu, January 25, 2018 3:08 pm, Robert LaJeunesse wrote:
> but I'll second Bill's section about including the power
> supply voltage regulator and bypassing.
Many of the SiLabs devices have on chip regulators, some of those may be
worth investigating.
--
Chris Caudle
The problem comes if the load current on the 1.8V regulator sees significant
ups and downs. Think output regulator in particular. Might also happen with the
digital core if major rollovers align and the core spikes. Those current
changes get spread (admittedly reduced, too) by the bypass caps, r
lajeune...@mail.com said:
> I'm sure you know the 1.8V supply regulators should not be fed from VDDA
> (3.3V), but I'll mention it anyway.
Why not?
That sounds like the sort of issue I should understand but I'm coming up
blank.
--
These are my opinions. I hate spam.
Yes, I was planning to include bypasses, and I've been convinced to put
at least the 1.8V regulator on the board as well. And to think about
the interconnects.
Adding the crystal does make the layout more complex -- they put a
ground pour on its own layer underneath it, and I think (but am no
John, I appreciate your minimalist goal, but I'll second Bill's section about
including the power supply voltage regulator and bypassing. Finding a good
regulator with wideband line regulation/rejection could prove a real search,
and such a fast chip as the Si5340 will need excellent broadband s
Hi
Things have to get pretty deep to be fully isolated from the seasons down to
the “digits past the decimal” level. It *does* bring up an interesting place to
set
up your temperature stabilized timing lab though. The commute back and forth
might be a bit of a chore :)
Bob
> On Jan 25, 2018,
On 1/25/18 12:12 PM, wb6bnq wrote:
Hi John,
Thanks for the response. Here is my 2 cents:
Well, due to the level of difficulty in chip mounting, I would prefer to
see a complete project. I.E., power supply for a single input of 12
volts and regulators the necessary chip values, proper input p
On 1/25/18 11:20 AM, Bob kb8tq wrote:
Hi
One of the unique features of underwater timing is that the sea bottom
temperature
(once you get well away from a coastline) is *very* stable. In some
deployments, the “random”
nature of ambient temperature that we fight all the time in the rest of the
Hi
Just to be clear, the current data sheet has the temperature range back to
-10 to +70C. They most certainly had a major headache on their hands for
several years straightening things out. I have not seen any complaints about
the “new” (post rework) version of the part.
Bob
> On Jan 25, 2018
On 1/25/18 9:39 AM, gandalfg8--- via time-nuts wrote:
At the time of writing a copy is available here
www.obsip.org/documents/Gardner_IEEE_Oceans_2016.pdf
"While results from an early batch of CSACs have been largely positive,
later units have not performed as well. The CSAC specifica
Hi Bill --
And that's exactly what I *don't* want to do. :-) The reason is that I
have several different projects in mind (and everyone else will have
their own requirements) and only want to deal with the difficult package
once.
The idea is to make a minimal carrier to deal with the tiny p
Hi John,
Thanks for the response. Here is my 2 cents:
Well, due to the level of difficulty in chip mounting, I would prefer to
see a complete project. I.E., power supply for a single input of 12
volts and regulators the necessary chip values, proper input protection
for the 10 MHz input leve
Hi Bill --
I should have been more clear: this design will be for a simple case:
one reference clock input, four outputs. The chip can do all sorts of
fancy tricks, but I'm looking for a source of four low jitter outputs
derived from a 10 MHz external reference (not using crystal or on-board
Hi
One of the unique features of underwater timing is that the sea bottom
temperature
(once you get well away from a coastline) is *very* stable. In some
deployments, the “random”
nature of ambient temperature that we fight all the time in the rest of the
world, simply is not
present. The devic
Hi
> On Jan 25, 2018, at 2:02 PM, wb6bnq wrote:
>
> Hi John,
>
> After looking at the data sheet, it seems way more involved then just making
> a carrier board for it. Besides the power supply requirements, various
> design selections would dictate different circuit layouts for different
>
> www.obsip.org/documents/Gardner_IEEE_Oceans_2016.pdf
Also see the very nice presentation:
"Challenges of precise timing underwater"
http://www.ipgp.fr/~crawford/2017_EuroOBS_workshop/Resources/Gardner_OBS_Timing_ATG_20150427.pdf
/tvb
___
time-nuts ma
Hi
> On Jan 25, 2018, at 12:39 PM, gandalfg8--- via time-nuts
> wrote:
>
>
>
> Hi
>
> The CSAC spec sheet calls out an aging rate of 0.9 ppb per month as
> “typical”. There is also a temperature spec of 0.4 ppb. If both are correct
> for your sample (*and* aging is linear ) you would be ou
Hi John,
After looking at the data sheet, it seems way more involved then just
making a carrier board for it. Besides the power supply requirements,
various design selections would dictate different circuit layouts for
different purposes. Even trying to do a general purpose application
woul
That's a wonderful paper by those Woods Hole guys.
Their temperature-compensated 5 milliwatt crystal oscillators can be
back-corrected (linear drift model) to a few tens of milliseconds over a
year and they make a convincing case they know how to do this.
Their similar graphs for CSAC oscillators
On Thu, Jan 25, 2018 at 7:32 AM, John Ackermann N8UR wrote:
>
> After the recent discussion about Silicon Labs clock generators, I looked
at their Si5340A part and think it will be useful for a ham radio project
I'm working on.
Have you considered the Si5340-EVB development board?
https://octopa
On Thu, 25 Jan 2018 09:32:56 -0500
John Ackermann N8UR wrote:
> http://www.silabs.com/documents/public/data-sheets/Si5341-40-D-DataSheet.pdf
>
> The challenge is that the chip is a 7x7 mm 44-QFN package and really
> wants to be put on a six-layer circuit board. That's doable, but
> challeng
Hi
The CSAC spec sheet calls out an aging rate of 0.9 ppb per month as
“typical”. There is also a temperature spec of 0.4 ppb. If both are correct
for your sample (*and* aging is linear ) you would be out by roughly 10 ppb
per year. There also is a voltage stability spec that might be impacted
For AllanTools and other testing I have tried the FFT plots in Stable32.
It seems to use a fairly simple FFT which has problems for divergent
noise-types. The Welch algorithm is better for these.
The x-axis should end at the Nyquist frequency, i.e. half of your data rate.
For meaningful phase-noise
After the recent discussion about Silicon Labs clock generators, I
looked at their Si5340A part and think it will be useful for a ham radio
project I'm working on. While it can do other things, for my use it
would use a 10 MHz input clock and generate 4 independent outputs in the
range of 100
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