See my pure "USB 2 SPDIF"

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Since almost everybody here got a PC, since almost everybody here got a DAC.
May everybody here, like me, want a "USB to SPDIF" .

Here, I've present a pure "USB 2 SPDIF" by using the universal PCM2902 ( http://focus.ti.com/lit/ds/symlink/pcm2902.pdf )
 

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Sure, it works. But don't you want it to work its best? Have you no desire to bring out the best performance possible? Just because it makes sound doesn't mean you stop there and be satisfied.

Look, you have LDO regulators onboard this chip, and to stabilize them you need some low impedance decoupling at their emitters (or sources). Otherwise the regulators can go wild. Sure, it might still work, but it is not good design to depend on decoupling at the other end of a USB cable. You are also allowing all of the RF noise from PC to enter the audio system.

Suggest you add an LC or a bead-C to filter this incoming 5V line.

jh
 
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