PCM1863EVM - white noise

Hirotaka Matsumoto

Other Parts Discussed in Thread: PCM1863EVM

Hi all,

Would you mind if we ask PCM1863EVM?

We heard from our customer that it occurred white noise following conditions using PCM1863EVM?

- Differential Input THD+N at - 1dBFS
- PGA: Gain(PGA) 12dB

We'd like to isolate the cause of this problem.
If you have some advice, could you let us know it?

We do need your help.

Kind regards,

Hirotaka Matsumoto

over 10 years ago

0 Justin Bohr over 10 years ago

TI__Mastermind 27990 points

Hi Hirotaka,

Do you have a THD+N result or an FFT of the output? Also what clock settings are they using and what input settings/pins are they using?

Justin

0 Hirotaka Matsumoto over 10 years ago in reply to Justin Bohr

Guru 27585 points

Justin sam

Thank you for your reply!

Now, we are hearing using your advice.
After that we will feed back.

Kind regards,

Hirotaka Matsumoto

0 Hirotaka Matsumoto over 10 years ago in reply to Hirotaka Matsumoto

Guru 27585 points

Justin san,

We are sorry that we confirm some information.

We got followings from our customer;
-Input: 7.5dBu(2.37*0.775=1.83675Vrms, 5.2Vp-p)
-Input frequency: 1kHz
-Clock: 48kHz, external
-Input type: Balance input

So, if you have some advice, could you let us know?

Kind regards,

Hirotaka Matsumoto

0 Hirotaka Matsumoto over 10 years ago in reply to Hirotaka Matsumoto

Guru 27585 points

Justin san,

We are sorry to bother you, but if you have some advice, could you let us know it?

Kind regards,

Hirotaka Matsumoto

0 Justin Bohr over 10 years ago in reply to Hirotaka Matsumoto

TI__Mastermind 27990 points

Hi Hirotaka-san,

I still don't have a clear picture of the situation, is it possible for you to show me the schematic or part of the schematic and an FFT of the output? Could you give me a THD+N measurement? The settings you have informed me about are valid settings that should meet the data sheet specifications. Noise could be caused by layout, clock issues, or an incorrect register setting. Another useful thing to have is a scope shot of the clocks and data from the device.

Justin

0 Hirotaka Matsumoto over 10 years ago in reply to Justin Bohr

Guru 27585 points

Justin san,

Thank you for your reply.
And we are sorry that our explanation is not clear.

-Our customer uses PCM1863EVM
So, we guess that the lay out is no problem.

We will check followings;
-FFT of the output
-THD+N measurement
-register setting

We need your help.

Kind regards,

Hirotaka Matsumoto

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PCM1863EVM - white noise