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TWL6040

eli
Guru 13485 points
Other Parts Discussed in Thread: TPA6132A2

n our smart glasses we have noises in the audio probably because wrong design.

We are using Variscite SOM that based on OMAP4460 with TWL6040 audio codec.

 

Because of real estate shortage we are using the micro USB connector for USB data/charging and for interface to our stereo earphone.

 

The analog stereo headphone (HSL, HSR) signals from the TWL6040 are mux with the USB signals, see the block diagram below.

Because the micro USB connector is connected to the digital ground we connected the headphone ground feedback (GNDHS) via

0 ohm resistor to the digital ground.

To verify that the connection to the digital GND is the cause to the noises I remove the 0ohm resistor and i connected the stereo headphone (HSL, HSR) signals

and the GNDHS directly to 3.5mm audio jack and the sound was clear without the noises.

 

We change the resistor to different values and we didn't notice any change in the intensity of the noise

 

I appreciate if you could help us on that.

 

One solution that I want to explore is to use TI TPA6132A2

any recommendation?

  • 0
    TI__Genius 17380 points
    Hi Eli,

    My only concern with the TPA6132A2 idea is if the OMAP is trying to do headphone detection using the HSL line, then the TPA6132A2 will interfere I think. If this feature isn't needed then it shouldn't be a problem (Figure 4-62 in the SWCS050E version of datasheet if you have that).

    Have you tried implementing the optional filter shown in some of the other Headset Load Model figures? I don't really understand the system with regards to how the USB goes out to the headset and how exactly the headset GND to digital GND connection is made, but this seems like a key point if the GNDHS to headset GND connection fixes the issue.