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Old 1st November 2012, 12:09 AM   #1381
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Quote:
Originally Posted by AR2 View Post
Hi guys,
I was wondering if any of you have solved this puzzle. Ian's S/PDIF board in its output uses U.FL connectors. Acko's DAC at input uses W.FL Hirose connectors. Any idea how to connect those two? I do not think they make any crossover cable that has both types of connectors. The only idea I have is to somehow switch U.FL connectors from S/PDIF board to W.FL, which I am sure is less than optimal from mechanical stand point, but I believe only possible one. Obviously my intention is to use those prefabricated cables, as they seem like really good solution.
Now I hope someone had a same problem with better idea. I absolutely hate those ultra small connectors. U.FL are quite fine and I hope Acko will replace his at some point to the bigger ones.
Hi AR2,

I really love those u.fl connectors and cables. They make the signal quality much better then any other regular cables. I tend to use them as possible as I could, you can say that.

Actually, anything before clock board is not that immportand, especially with the isolator board. Having nothing wrong on data is the only thing I ask for. So, ph2.0mm calbles don't have any problem. Only need ground wires between signals if Fs higher then 176/196KHz. However, anything after clock board is critical. So, coaxial (U.FL) cable is almost a must for those low jitter high speed applications.

I didn't try w.fl. Seems a bit diffcult to solder. Fortunately, qusp mentioned that w.fl can share same footprint as u.fl. Replacing those smt sockets is very easy.

I'm afraid there would be kind of w.fl to u.fl bridge cable, but I just couldn't source it.

Ian
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Old 1st November 2012, 12:42 AM   #1382
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Quote:
Originally Posted by marce View Post
The GND (return path) should be adjacent to the signal, when you start getting into 100MHz signals, you can easily inroduce signal integrity problems. The main concern is avoiding impedance mismatches as you go from on board to another, and distance is also critical, they dont like going a long way, depending on the driver, receiver and cable used for transmission.
Samtecs range of high speed cables to give you an idea of what is used for high speed signal transmission:
Samtec | High Speed Cable Assemblies
Another methos widely used is either FPC/FFC connectors and cables or bespoke two plus layer flex caqbles with a ground plane and the respective connectors. Preferably the signal should travel over a contigous return plane (GND) from transmittor to receiver, or if only one or two signals then co-ax cable with rf connectors.
The frequencies that are of concern are determined by the knee frequecy:
Fknee=1/2tr where tr is the 10-90% rise time of the signal.
This is also the determining factor on whether a design is high speed, not the ultimate clock frequency.

The following links are some of the main people for signal integrity:

beTheSignal.com
Signal Consulting, Inc. - Dr. Howard Johnson
Speeding Edge consultants specialize in high-speed PCB and system design disciplines
Hi marce,

Thank you for sharing your RF knowledge with us. You are expert on RF and high speed layout design. I always have to keep in mind those tips with my designs, otherwise I will have troubles in those EMC labs. Passing all the EMC tests is a basic requirement for FDA registration.

Totally agree with you, RF signal has to be treated as analog signal. Clock signal have to be treated as RF signal.

Do you have some on line simulation on RF signal transmition over coaxial cable or transmition line? If so, that would much easier to understand the principles.

Talking about the raising time, matching on the source with a serial resistor is a very common method, but it will make the rasing edge a bit slower. Or, you have to use end termination. I'm not quite sure which way is better for the low jitter performance, with or without. On the new designed Si570 clock board, I'll leave a optional u.fl socket footprint for a MCLK signal without source serial resistor, will see, which way is better .

Ian
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Old 1st November 2012, 12:46 AM   #1383
AR2 is offline AR2  United States
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Ian and Qusp,

Thank you for the prompt reply. Yes I am clear that besides clock, any other cabling is done without U.FL cables. I have it put together with cables provided by Ian. I did replacement of U.FL to W.FL connectors, previously on my LightHarmonics USB to I2S board, because of the same problem - incompatibility with ACKOP board. I was just hoping someone is smarter ( not hard at all) and found some better solution. W.FL connectors are very small, compared to U.FL that are much easier for handling. Yes it is correct that w.FL will fit into U.FL footprint, but knowing how tight is connection between cable and plug, I always worry that I will pull trace with that little bugger, even if I am using that expensive tool, that I purchased. With U.FL socket in its place, at least I have a feel that connection between board and socket is much stronger.
Thanks a lot guys!
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Old 1st November 2012, 03:10 AM   #1384
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Default BOM of standard configuration of Passive Battery Management Board

Testing group start receiving the PCB. Someone may get bit confusion on the schematics and BOM. Actually the standard configuration is very simple, just a couple of components. I post a picture of this configuration below. It should be a good start point. More features could be added step by step later on. Just hope it’s clear enoughJ.

(nothing on the bottom side)

Ian
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File Type: jpg DefaultBOM.jpg (139.1 KB, 372 views)
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Old 1st November 2012, 09:20 AM   #1385
koldby is offline koldby  Denmark
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Default A good chain?

Hi.
What about this configuration:
USB isolator (ADuM4160 USB Isolator board by Circuits@Home [CAH-ASSY-UI] - 44,90*€ : lipoly.de, Alles für den Elektromodellflug.) - to - USB to I2S Audio Widget (Q N K T C USB-I2S Module and Analog Board) - to - I2S FIFO - to - DAC

Thanks

Koldby
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Old 1st November 2012, 09:29 AM   #1386
qusp is offline qusp  Australia
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it will work yes, but I think its a better idea to use the isolator on the fifo
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Old 1st November 2012, 12:58 PM   #1387
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After burnt in the isolator board for a week, details are increasing with much quite background. I still have not isolate the I2C as RS has not delivered my order yet.

I hope other testers can also report their progress.
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Old 1st November 2012, 01:11 PM   #1388
qusp is offline qusp  Australia
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waiting for my fifo to get back, not much can be done before then
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Old 1st November 2012, 01:41 PM   #1389
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Quote:
Originally Posted by bigpandahk View Post
After burnt in the isolator board for a week, details are increasing with much quite background. I still have not isolate the I2C as RS has not delivered my order yet.

I hope other testers can also report their progress.
You mean you have already ordered the I2C isolator? I usually receive digikey orders in two days.

Please confirm the datasheet with the PCB footprint, I didnt do it.

Ian
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Old 1st November 2012, 01:54 PM   #1390
syklab is offline syklab  Hong Kong
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Quote:
Originally Posted by bigpandahk View Post
After burnt in the isolator board for a week, details are increasing with much quite background. I still have not isolate the I2C as RS has not delivered my order yet.

I hope other testers can also report their progress.
Hi,
Which isolator are you planing to use for I2C ?
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