Schematic review request for the ADAU1761.
Hi David,
As I have posted in the wrong space (Precision Microcontrollers), Now I am posting in the sigma DSP section.
Now I am replying to the answer mentioned in the Precision Microcontroller section,
In the Line Outputs section of the ADAU1761 datasheet, the following statement is provided:
"The MX5G4[1:0], MX5G3[1:0], MX6G3[1:0], and MX6G4[1:0] bits can all provide a 6 dB gain boost to the line outputs. This gain boost allows single-ended output signals to achieve 0 dBV (1.0 V rms) and differential output signals to achieve up to 6 dBV (2.0 V rms)."
Could you please verify whether the specification indicating 2.0 Vrms differential output is correct?
Also, I plan to use the Line Out pins as headphone outputs by setting the LOMODE (R31) and ROMODE (R32) bits.
kindly review the shared schematic and confirm whether the implementation is appropriate for headphone mode operation, both for 16 Ω loads and for higher impedance headphones.
Regards,
Muthu
hardware
processors and dsp
adau1761
Processors and Microcontrollers
Hello Muthu,
It is a little difficult for me to answer some of these questions because all the people who were on this design project are no longer here. So I grabbed an eval board and made some measurements.
I suggest you also mock up your design to verify it will do what you need.
I setup a project to output a full-scale sine wave out of the core. Then I measured the differential output with a multimeter.
With the output volume control set to 0dB I measured 0.925Vrms
With the output volume control set to +6dB I measured 1.87Vrms
This is very close to what the datasheet says for single ended output level of 0.92Vrms
So differentially it will not quite reach 2.0Vrms
Regarding setting the line output pins to headphone mode I am not as confident in this. I would use the actual headphone output pins. The datasheet does provide specifications for a 16 ohm load on the headphone output pins so it will do 16 ohms and higher than that will not be a problem.
Dave T
Hello Muthu,
Also, Have you downloaded and looked at the evaluation board user guide? UG-119.
Dave T
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