I'm working on a circuit for audio output from a Teensy 4.1 using as PCM5100 I2S DAC and a TPA6111 amp.


I'm wondering if the circuit, specifically the headphone out (circuitry around U23) looks viable. I want the headphone output to be able to drive both low and high impedance headphones.


"Out L" and "Out R" are line out. I've used the line out circuit before, so I know the part up until the line out jacks are working.


Any feedback is welcome!

 

I am not familiar with that "U23" device, , but I think that I see a problem, which is that you appear to have the "shutdown" biased on.
I suggest studying the data sheet on that device.

 

The datasheet shows the output into minimum 8 Ohms. How low do you want to go?

 

Any feedback is welcome!

The shutdown pin needs to be grounded for normal operation.
May need volume controls on the inputs of the amp.

 

What would you consider high impedance headphones? If you mean above 80 ohms or so, you won't drive much power into them from a 5V supply.

 

I want the headphone output to be able to drive both low and high impedance headphones.

That IC should deliver adequate power to headphones from 8Ω to to above the 32Ω for typical consumer units.

 

Some observations
PCM5100 needs an RC output filter and you have none, going to the TPA6111. R20 does nothing, you need a 0R added if you trying to add the muste etc. SCK pin is grounded when using the PLL. I would add a ferrite bead to AVDD, it needs clean power.

 

Some observations
PCM5100 needs an RC output filter and you have none, going to the TPA6111. R20 does nothing, you need a 0R added if you trying to add the muste etc. SCK pin is grounded when using the PLL. I would add a ferrite bead to AVDD, it needs clean power.

Really, that R20 DOESwaste power. Certainly it provides no benefit. It would pull down the XSMT terminal if it were not pulled up by the direct connection. You will need to read the data sheet to discover which way it should be biased.
AND I agee that since I see no level control, you may need to add one.