• State
  • Locked Locked
  • Replies 2 replies
  • Subscribers 29 subscribers
  • Views 3314 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

About PCM5102A

Fai Chan
Intellectual 440 points
Other Parts Discussed in Thread: PCM5102A, PCM1861

Hi TI experts, 

I have some questions about PCM5102A as below, I appreciate your help. 

Fai~

In my system, there are different audio signal input to the system and using PCM5102A is an analog output terminal for headphone. 

Case 1: PC's headphone(SE) signal output to (ADC)PCM1861 without gain to generate I2S signal to the Amp & (DAC)PCM5102A. 

Question 1 : The Vrms from PC is 1.3V, and 5102A's output Vrms is 1.2xV, so there is about 0.05V ~ 0.1V different. is it normal ? or is 5102A supposed to generate the exact same Vrms level as the original level from PC ? 

Question 2 : Are the below scenarios caused by the LowPassFilter or the Anti-aliasingFilter or other reasons?. I want to reconstruct the analog signal precisely from 5102A which can (1) have same loudness as the original signal from PC. (2) maintain a clean signal in full range frequency.

  • Scenario A: Anti-aliasingFilter added for analog input to PCM1861, and a LowPassFilter added for analog output from 5102A.                                              Result : (1) the loudness from 5102A is about 50% weaker than the original loudness from PC. (2) the signal is not really good from 5102A's output in high frequency range from 10Khz to higher
  • Scenario B: When i took out the LowPassFilter from 5102A's output.                                                                                                                                           Result : (1) the loudness from 5102A become same as the original loudness from PC. (2) the signal is bad in high frequency range from 10Khz to higher.

Case 2: Using TI's USB-I2X board connected to PC as a soundcard to generate the I2S signal to PCM5102A

Question 1: same scenarios and results happen as above Case 1's question 2_scenario A and B

*** The anti aliasing filter to PCM1861 and the circuit of PCM5102A (with LowPassFilter)  is show as below. 

*** The signal is shown as below ( Top is the original signal ) , (Middle is after 5102A with LowPassFilter) , ( Botton is after 5102A without LowPassFilter )