TPA6120A2: Load Parallel TPA6120A2

Hello Sumathi,

I can review this behavior for you.  

Can you confirm the top amplifier is doing differential input to differential output amplification?  It appears the bottom amplifier is being used in a single-ended input to single-ended output.  

There may be circuit changes necessary to drive the same headphone with both stereo (top amp) and mono (L channel bottom amplifier). 
Are you using only one amplifier at a time?

Best,

Alec

Hi Alec,

Thanks for the response.

In the top amplifier, there are two single-ended inputs and two single-ended outputs. One of the single-ended inputs is connected to the Left op-amp, while the other is connected to the Right op-amp.

All amplifiers are utilized at a time, sometimes only one amplifier is in use. Note that all the amplifiers are single-ended audio inputs and audio outputs.

Thank You,

Sumathi

Hello Sumathi,

This may be an issue in the impedance seen by each amplifier.  Are the output voltage fluctuations repeatable, consistent, or random?

Best,

Alec

Hi Alec,

the output voltage fluctuations are repeatable and sometimes it will be consistent while doing testing.

Thank You,

Sumathi K

Hello Sumathi,

Are the resistors shorting the outputs to GND present on the board, or are those DNI/DNP and not populated?

Best,

Alec

Hi Alec,

The resistors R30, R31 and R38 are DNP.

Thank You,

Sumathi K

Hello Sumathi,

Thank you, that is what I had thought when I viewed the schematic.

What bench equipment or measurement setup are you using to test/probe the three amplifier channel outputs?

Best,

Alec