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Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter
Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter
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Old 19th December 2012, 11:10 PM   #1721
iancanada is offline iancanada  Canada
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Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter
Quote:
Originally Posted by hochopeper View Post
Since we're discussing layout, Ian I notice that you use a separated copper section on each mounting point, is there a reason for this?

Cheers,
Chris
Chris

Oh, That's not a special issue, just for eliminating the possible loop, otherwise the surrounding EMI noise will generate current within as an antenna. Actually all the mounting holes should be connected to the metal case to keep the noise as low as possible, and not to be 'island' at same time.

Ian
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Old 19th December 2012, 11:28 PM   #1722
hochopeper is offline hochopeper  Australia
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Thanks Ian


I know its not a particularly critical issue for the device's performance, I just was curious to learn the reasoning, because like you say they're each attached to the enclosure and it was just something that I hadn't noticed before. It seemed as though you'd gone out of your way to do it intentionally so I thought I'd ask since your designs tend to not do things without a good reason!


Chris
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Old 20th December 2012, 12:04 AM   #1723
iancanada is offline iancanada  Canada
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Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter
Quote:
Originally Posted by hochopeper View Post
Thanks Ian


I know its not a particularly critical issue for the device's performance, I just was curious to learn the reasoning, because like you say they're each attached to the enclosure and it was just something that I hadn't noticed before. It seemed as though you'd gone out of your way to do it intentionally so I thought I'd ask since your designs tend to not do things without a good reason!


Chris
Yes, that right. If not be connected to the GND of the case, the coppers will become islands, for high frequency, that even worth then nothing.

Ian
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Old 20th December 2012, 02:58 PM   #1724
MisterRogers is offline MisterRogers  United States
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Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter
Ordering parts for the TPS7A4700 boards; What should I order for D1 (LED)? R9 can be pretty much any 1K 1206, right? Thanks in advance for your help :-)
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Old 20th December 2012, 03:43 PM   #1725
iancanada is offline iancanada  Canada
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Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter
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Originally Posted by MisterRogers View Post
Ordering parts for the TPS7A4700 boards; What should I order for D1 (LED)? R9 can be pretty much any 1K 1206, right? Thanks in advance for your help :-)
MisterRogers

For TPS7A4700 reg PCB, package of both LED D1 and R9 is 0603.

Yes for red yellow or green, R9 can be 1K with 3.3V output. But if you want blue or white LEDs, you have to make sure the Vf is less than 3V, and R9 may also be reduced.

Anyway, D1 and R9 are just for power indication. You can keep them un-assembled if you donít need them .

Ian
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Old 20th December 2012, 11:45 PM   #1726
necplusultra is offline necplusultra  Canada
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Greetings,

I finaly tried out the isloator board but I cannot seem to have a lock on the input.

I verified shorts on the resistor array and they checked out good with no shorts.

I don't know where to go from here.
any help appreciated.
thanks
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Old 21st December 2012, 12:27 AM   #1727
necplusultra is offline necplusultra  Canada
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MY BAD.

I think with the isolator in circuit, the clock has to be powered externally.

I could not find instructions on accomplishing this except something about removing L11

Are there any pads and what voltage is expected?
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Old 21st December 2012, 12:31 AM   #1728
iancanada is offline iancanada  Canada
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Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter
Quote:
Originally Posted by necplusultra View Post
Greetings,

I finaly tried out the isloator board but I cannot seem to have a lock on the input.

I verified shorts on the resistor array and they checked out good with no shorts.

I don't know where to go from here.
any help appreciated.
thanks
Please confirm everything is OK without the isolator board. If so, you can lock the problem on the isolator board.

Please check not only the short, but also disconnect. The resistor is 33ohm. Please reference the schematics I posted. Also confirm the part number of isolator is correct.

Good luck.

Ian
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Old 21st December 2012, 12:33 AM   #1729
iancanada is offline iancanada  Canada
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Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter
Quote:
Originally Posted by necplusultra View Post
MY BAD.

I think with the isolator in circuit, the clock has to be powered externally.

I could not find instructions on accomplishing this except something about removing L11

Are there any pads and what voltage is expected?
Yes, with the isolator board, you have to power the clock board externally. If you use the dual xo clock board, the power is 5V DC.

Ian
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Old 21st December 2012, 12:37 AM   #1730
iancanada is offline iancanada  Canada
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Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter
Quote:
Originally Posted by necplusultra View Post
MY BAD.

I think with the isolator in circuit, the clock has to be powered externally.

I could not find instructions on accomplishing this except something about removing L11

Are there any pads and what voltage is expected?
I guess you didn't read the fifo pdf file with careful . I attach it again, please see the last page.

Good luck

Ian
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File Type: zip IanFIFOKITGBIII.zip (693.6 KB, 66 views)
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