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How to properly terminate unused S/PDIF pins in a DAC (PCM2903C)?
How to properly terminate unused S/PDIF pins in a DAC (PCM2903C)?
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Old 17th July 2018, 11:02 PM   #1
MaverickPT is offline MaverickPT  Portugal
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Question How to properly terminate unused S/PDIF pins in a DAC (PCM2903C)?

I've been told that leaving pins that aren't being used and leaving simply disconnected is a bad idea. That will increase power consumption, noise, etc. I know how to do it in a op amp, but I'm having some difficulty with this DAC chip. I won't use the S/PDIF function.

PCM2903C Stereo USB1.1 CODEC with line-out and S/PDIF I/O, Self-powered (HID Interface) | TI.com

I'm guessing that the S/PDIF input should be tied to ground, should I take any other precaution? And what about the output? If I do the same to it, won't that possibly blow the chip due to overcurrent, or create noise of some kind? Should it be connected with a resistor? A capacitor in parallel? How should it be done?
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Old 17th July 2018, 11:19 PM   #2
MaverickPT is offline MaverickPT  Portugal
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Ok, so while looking at the datasheet of the PCM2900C, a very similar DAC without S/PDIF it says to connect the S/PDIF input to gnd and leave the output floating. Should I do this too?

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Old 18th July 2018, 12:44 AM   #3
MaverickPT is offline MaverickPT  Portugal
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Yeah probably this is the answer. Typical me finding the answer after I publish a question in a forum! :facepalm:
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Old 18th July 2018, 01:28 AM   #4
rfbrw is offline rfbrw
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You reached this conclusion having read the datasheet ?
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Old 18th July 2018, 01:30 AM   #5
MaverickPT is offline MaverickPT  Portugal
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Quote:
Originally Posted by rfbrw View Post
You reached this conclusion having read the datasheet ?
In my defense, it was the datasheet from a slightly different chip \_(ツ)_/
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Old 18th July 2018, 03:37 AM   #6
rfbrw is offline rfbrw
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The correct datasheet states the SPDIF input already has a pull-down resistor.
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Old 18th July 2018, 03:41 AM   #7
MaverickPT is offline MaverickPT  Portugal
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Quote:
Originally Posted by rfbrw View Post
The correct datasheet states the SPDIF input already has a pull-down resistor.
Ah. I missed that. I feel even dumber now

Thank you for helping a dummy!
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