PCM1802: BYPAS set on HIGH, but no DC component on DOUT

Filip Gjorgjevski

Part Number: PCM1802

Hi,

I making a project for school and am using the PCM1802. I connected it and it works normal when I put something on the input (Analog output). Right now I want to see the difference when I set THE BYPAS on HIGH to see the DC on the output. Unfortunately It does not work ( it still only shows only the ANALOG). I even connected 2V to the input to have a pure DC input and it showed nothing on the DOUT. What can be the cause of that? Can it be solved?

Thank you in advance,

Filip

over 4 years ago

0 Zak Kaye over 4 years ago

TI__Mastermind 23050 points

Hi Filip,

Generally you will have AC coupling caps on your input and the signal will be internally biased to mid-supply by the onboard reference, so you may not see valid data if you put 2Vdc at the input. The bypas pin will include the internal dc offset applied to the signal. What are you using to interpret the audio data? Perhaps your signal analyzer is still applying a high pass filter?

best,

Zak

0 Filip Gjorgjevski over 4 years ago in reply to Zak Kaye

Prodigy 50 points

Hi Zak,

I'm using and XMOS soundcard without a HPF. The problem that I'm having is that it doesn't show any changes to the output signal when I apply or increase the DC offset during the BYPAS is on high. I even used a function generator to generate a sine wave and then slowly increase the DC offset and it doesn't made any changes to the DOUT.

Filip

0 Zak Kaye over 4 years ago in reply to Filip Gjorgjevski

TI__Mastermind 23050 points

Hi Filip,

Is the PCM1802 on the XMOS soundcard or are you using a TI EVM to interface with the soundcard? I would recommend checking the schematic and board to make sure there are no AC coupling caps still on the input.

best,

Zak

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PCM1802: BYPAS set on HIGH, but no DC component on DOUT