AUDIO DAC POWER CONTROL
AUDIO ANALOG INPUTS
Gain=0, –1.5, –3,..., –12dB,Mute
ToLeft ADCPGA
B0156-03
LINE1LP_x
LINE1RM_x
Gain=0, –1.5, –3,..., –12dB,Mute
Gain=0, –1.5, –3,..., –12dB,Mute
LINE2LP_x
LINE1LM_x
LINE2LM_x
LINE1RP_x
TLV320AIC34
SLAS538A – OCTOBER 2007 – REVISED NOVEMBER 2007
Table 6. Analog Output Common-Mode Recommended Settings
CM SETTING RECOMMENDED AVDD, DRVDD RECOMMENDED DVDD
1.35 V 2.7 V – 3.6 V 1.65 V – 1.95 V
1.5 V 3 V – 3.6 V 1.65 V – 1.95 V
1.65 V 3.3 V – 3.6 V 1.8 V – 1.95 V
1.8 V 3.6 V 1.95 V
The stereo DAC can be fully powered up or down, and in addition, the analog circuitry in each DAC channel can
be powered up or down independently. This provides power savings when only a mono playback stream is
needed.
The TLV320AIC34 includes 20 analog audio input terminals, 10 for each partition. The 10 inputs in each partition
can be configured as up to four fully differential pairs plus one single-ended pair of audio inputs, or up to six (or
eight, if LINE2(L/R)M to line bypass are considered) single-ended audio inputs. These ten terminals connect
through series resistors and switches to the virtual ground terminals of two fully differential operational amplifiers
(one per ADC/PGA channel). By selecting to turn on only one set of switches per operational amplifier at a time,
the inputs can be effectively multiplexed to each ADC PGA channel.
By selecting to turn on multiple sets of switches per operational amplifier at a time, mixing can also be achieved.
However, single-ended and fully differential audio inputs cannot be mixed into the same ADC PGA at the same
time. Mixing of multiple inputs can easily lead to PGA outputs that exceed the range of the internal operational
amplifiers, resulting in saturation and clipping of the mixed output signal. Whenever mixing is being implemented,
the user should take adequate precautions to avoid such a saturation case from occurring. In general, the mixed
signal should not exceed 2 Vp-p single-ended or 4 Vp-p fully differential.
In most mixing applications, there is also a general need to adjust the levels of the individual signals being
mixed. For example, if a soft signal and a large signal are to be mixed and played together, the soft signal
generally should be amplified to a level comparable to that of the large signal before mixing. In order to
accommodate this need, the TLV320AIC34 includes input level control on each of the individual inputs before
they are mixed or multiplexed into the ADC PGAs, with gain programmable from 0 dB to – 12 dB in 1.5-dB steps.
Note that this input level control is not intended to be a volume control, but instead used occasionally for level
setting. Soft-stepping of the input level control settings is implemented in this device, with the speed and
functionality following the settings used by the ADC PGA for soft-stepping.
The TLV320AIC34 supports the ability to mix up to three fully differential analog inputs into each ADC PGA
channel. Figure 30 shows the mixing configuration for the left channel of one partition, which can mix the signals
LINE1LP_x, LINE1LM_x, LINE2LP_x, LINE2LM_x, LINE1RP_x, and LINE1RM_x of the associated partition.
Figure 30. Left-Channel Fully Differential Analog Mixing Capability
Copyright © 2007, Texas Instruments Incorporated Submit Documentation Feedback 41
Product Folder Link(s): TLV320AIC34
(7 pages)
Manymanuals.com
Manymanuals.de
Manymanuals.fr
Manymanuals.it
Manymanuals.pl
Manymanuals.cz
Manymanuals.es
Manymanuals-pt.com
Comments to this Manuals