TLV320AIC3107_15 Datasheet, PDF (21/100 Pages) Texas Instruments – TLV320AIC3107 Low-Power Stereo Codec With Integrated Mono Class-D Speaker Amplifier

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Feature Description (continued)
TLV320AIC3107
SLOS545D – NOVEMBER 2008 – REVISED DECEMBER 2014
word
clock
bit clock
data
in/out
DSP Mode
offset
N-1 N-2
1 0 N-1 N-2
10
Left Channel Data
Right Channel Data
word
clock
bit clock
data
in/out
Left Justified Mode
N-1 N-2
10
N-1 N-2
10
offset
Left Channel Data
offset
Right Channel Data
Figure 18. DSP Mode and Left Justified Modes, Showing the
Effect of a Programmed Data Word Offset
10.3.3 Audio Data Converters
The TLV320AIC3107 supports the following standard audio sampling rates: 8 kHz, 11.025 kHz, 12 kHz, 16 kHz,
22.05 kHz, 24 kHz, 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, and 96 kHz. The converters can also operate at
different sampling rates in various combinations, which are described further below.
The data converters are based on the concept of an Fsref rate that is used internal to the part, and it is related to
the actual sampling rates of the converters through a series of ratios. For typical sampling rates, Fsref will be
either 44.1 kHz or 48 kHz, although it can realistically be set over a wider range of rates up to 53 kHz, with
additional restrictions applying if the PLL is used. This concept is used to set the sampling rates of the ADC and
DAC, and also to enable high quality playback of low sampling rate data, without high frequency audible noise
being generated.
The sampling rate of the ADC and DAC can be set to Fsref/NDAC or 2×Fsref/NDAC, with NDAC being 1, 1.5, 2,
2.5, 3, 3.5, 4, 4.5, 5, 5.5, or 6.
While only one Fsref can be used at a time in the part, the ADC and DAC sampling rates can differ from each
other by using different NADC and NDAC divider ratios for each. For example, with Fsref=44.1-kHz, the DAC
sampling rate can be set to 44.1-kHz by using NDAC=1, while the ADC sampling rate can be set to 8.018-kHz by
using NADC=5.5.
When the ADCs and DACs are operating at different sampling rates, an additional word clock is required, to
provide information regarding where data begins for the ADC versus the DAC. In this case, the standard bit clock
signal is used to transfer both ADC and DAC data, the standard word clock signal is used to identify the start of
the DAC data, and a separate ADC word clock signal (denoted ADWK) is used. This clock can be supplied or
generated from GPIO1 at the same time the DAC word clock is supplied or generated from WCLK.
10.3.3.1 Audio Clock Generation
The audio converters in the TLV320AIC3107 need an internal audio master clock at a frequency of 256×Fsref,
which can be obtained in a variety of manners from an external clock signal applied to the device.
A more detailed diagram of the audio clock section of the TLV320AIC3107 is shown in Figure 19.
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