Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter - Page 230 - diyAudio
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Old 29th January 2013, 07:05 PM   #2291
qusp is offline qusp  Australia
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yes, it kinda does
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Old 30th January 2013, 07:46 AM   #2292
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Different question: What are the best clock to try while waiting for the S571 ? I have already the crysteks 957 and the tentclock. I read somewhere ndk el, not sure which one exactly..., joe rasmussen voting for saw types, but for the fifo their frequencies are too high, anything else ?

Decoupling: what is best in terms of setup and parts ? Tent votes for a coil/ choke and a smal 0,1uf cap...any other advises ?

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Old 30th January 2013, 09:23 AM   #2293
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All around -100/105 dBc@10Hz in phase noise (Silicon Labs, Tentlabs, Crystek, NDK), not a great difference, save money and build a simple picogate oscillator as in the Rakon document, possibly using a good crystal.

Decoupling: a good cap just close to the oscillator.
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File Type: pdf IC_CRYSTAL_OSCILLATOR_CIRCUITS (1).pdf (82.2 KB, 81 views)
File Type: pdf sn74lvc1gx04.pdf (783.8 KB, 47 views)
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Old 30th January 2013, 10:35 AM   #2294
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yeah, because my time is worth so little that designing, building and trimming a high speed low noise CMOS design works out cheaper....
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Old 30th January 2013, 12:08 PM   #2295
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on the note of clocks qusp, asked a question on the GB thread regards your thought process on something you said. Just trying to remember what it was.....
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Old 30th January 2013, 12:30 PM   #2296
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what do you think is there inside a Crystek or a Tentlab oscillator?
I tell you that, a simple picogate oscillator and cheap crystal, phase noise specs talks itself.
Rakon has already design for you, just open the document, not more than six components (8 in case of overtone crystals). 74HCU04 have gain beyond 100MHz, so no speed problems.
Rf=2M2, Rlim=180R, C1=10p, C2=470p, are a good starting point.
Since probably you don't own an Agilent phase noise measurement system, just look at the waveform with a scope and listen how it sounds. Buy a bag of Citizens cylindrical crystal from farnell (0.3 USD each) and find the best. Better, if you have a source, buy a good crystal (that do not costs much more than a Crystek osc).
Finally you'll reach at least -115dBc@10Hz in phase noise.

All the above oscillators are already trimmed and tested for you, and perform worst than what you can build yourself (take a look at their specs).
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Old 30th January 2013, 02:06 PM   #2297
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How would this compare to a S571 ? wha would Ian not have designed such a device already when it is so much better and so easy to achieve ? And what do you consider a good crystal ? MAybe I give it a try.

Last edited by Blitz; 30th January 2013 at 02:10 PM.
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Old 30th January 2013, 02:38 PM   #2298
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Quote:
Originally Posted by iancanada View Post
Since on board LDO is removed, 3.3V regulator is now open to the external power supply solution from 3P SIP connector TP3,TP4,TP5. Where TP5=VIN;TP4=GND;TP3=VOUT; quite standard pin out. High quality low noise external power supply could be integrated with this clock board to boost the Si570 performance. Different power solutions can be experienced and selected according to personal preference.
Some of the possible power solutions are:

1, TPS7A4700 low noise LDO board
This reg board is confirmed to be one of the best LDO boards so far to power the clock board. You can connected to it by plugging into the 3P SIP socket, but it would be better to be soldered directly to the pins once you decided to stick with it. TPS7A4700 reg board could be placed both in vertical and in horizontal position to the clock board.

2, Third party 3PIN reg boards
We will have many choices such as TP 3.3V Trident and etc. But have to make sure the output current is enough to power Si570 clock board which is rated at 150mA.

3, Shunt regulators
Any 3.3V Shunt regulator can work for the Si570 clock board. But the high frequency performance has to be confirmed suitable powering oscillators.

4, Direct 3.4V LiFePO4 battery cell
To achieve this configuration, we have to
(1), Running Si570 clock board with an isolator board or in stand along mode
(2), Short VIN and VOUT pins by a jumper
(3), Connect to a 3.4V LiFePO4 battery cell or battery management board from DC input connector J2.
If running with an isolator board, half of the isolator board will be powered by the same 3.4V battery automatically from 10P FFC/FPC cable. Usually we dont need remove or bypass the LDO on isolator board because most of LDOs is tested still be capable enough to power the half isolator with 3.4V input (the output will be a bit lower than 3.3V).

5, Standard TO220-3 3.3V 3 terminal regular IC
We can find tons of those LDOs, such as 78M33, for testing is OK. But not recommended for real operating because of the noise performance.

Please note, a good linear regulator for an audio amplifier may no longer be good for an oscillator. To power a XO, we need a regulator not only has perfect low noise performance but also can keep that good performance for high frequency RF/VCO applications.

Ian
I dont know if anyone ask this before, but wouldnt it be cool to have such an option also on the single/dual clock board?

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Old 30th January 2013, 02:50 PM   #2299
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what are you asking? regs? do you really think it hasnt been discussed before about good regs in 230 pages? hehe. of course you know it has. its been deliberately left to us there is no pleasing everyone
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Old 30th January 2013, 02:51 PM   #2300
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The TPS7A4700 low noise LDO board.
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