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6.6
Audio Input/ADC Tab
Kit Operation
Next to the time domain plots, calculated values of SINAD, SNR, and THD are shown. These values are
all expressed in dB relative to the full-scale of the TLV320AIC32. Note that the SNR number shown is
A-weighted.
In
Figure 4
, a sine wave generated by the TLV320AIC32 DACs is fed through the high power drivers and
back into the ADC; then the resulting FFTs can be seen. Note that this sequence is a full analog loopback
test case, so the measured numbers show the combined performance of the DAC, drivers, and ADC.
There is also no post-DAC filtering; as noted in the data sheet, this may degrade measurements even
though there is no audible noise.
The Audio Input/ADC Tab is laid out like an audio mixing console. Each input channel has a vertical strip
that corresponds to that channel. LINE1L and LINE1R input strips have controls to route that input to
either the left or right ADC input; by default, all inputs are muted when the TLV320AIC32 is powered up.
To route an input to the ADC, first click on the MUTE button in the input channel strip which corresponds
to the ADC input channel you want that input to go to—the caption on the button will change to ACTIVE.
The level of the input channel routed to that particular ADC channel can then be adjusted using the Level
knob below the MUTE/ACTIVE button. See
Figure 5
.
Figure 5. Audio Input Tab
TLV320AIC32EVM and TLV320AIC32EVM-PDK User's Guide
14
SBAU113 – November 2005
