Is it possible to directly connect PCM1789 DAC to TPA6138A2 headphone amplifier?

According to datasheet PCM1789 output are differential outputs and the input of TPA6138A2 is also differential inputs. The PCM1789 datasheet suggest putting LPF/Differential to single ended circuit. I wanted to know whether this LPF/Differential to single ended circuit can be avoided and make a direct connection.

It's my first time for all this so I needed some guidance.

pcm1789: http://www.ti.com/lit/ds/symlink/pcm1789.pdf tpa6138a2: http://www.ti.com/lit/ds/symlink/tpa6138a2.pdf


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Your design should follow this circuit in TPA6138 datasheet. If you notice carefully, this is in fact a differential to single ended circuit.

  • \$\begingroup\$ yes, but can you confirm that one can connect the output of the PCM1789 to the input of TPA6138 directly? \$\endgroup\$ – ravikumar Aug 1 '17 at 10:57
  • \$\begingroup\$ No you can't. The DAC reference voltage is 2.5V, a DC blocking cap must be use. If you want direct connection, choose another DAC that has dual supply. \$\endgroup\$ – Jason Han Aug 1 '17 at 13:42
  • \$\begingroup\$ do you think DC blocking cap of 0.1uF between the DAC and TPA6138 might work(to each inputs)? for example in the figure above, the C3 can be 0.1uF blocking the DC of the incoming audio signal? \$\endgroup\$ – ravikumar Aug 1 '17 at 14:01
  • \$\begingroup\$ That's not enough, you need to study low pass filter design for your audio application. Aim for 40kHz low pass filter with at least 10uF cap. \$\endgroup\$ – Jason Han Aug 1 '17 at 14:49
  • \$\begingroup\$ as mentioned in PCM1789 DAC datasheet, i had LPF/diff. to single circuit connected at its output but then output will be single ended(total 2 o/p) but the TPA6138 expects differential inputs(total 4 i/p) \$\endgroup\$ – ravikumar Aug 1 '17 at 15:11

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