Datasheet
DIGITAL AUDIO PROCESSING
H(z) +
N0 ) N1 z
*1
32768 * D1 z
*1
(1)
ǒ
N0 ) 2 N1 z
*1
) N2 z
*2
32768 * 2 D1 z
*1
* D2 z
*2
Ǔǒ
N3 ) 2 N4 z
*1
) N5 z
*2
32768 * 2 D4 z
*1
* D5 z
*2
Ǔ
(2)
LB1 LB2
RB1 RB2
TLV320AIC31
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............................................................................................................................................. SLAS497C – AUGUST 2006 – REVISED DECEMBER 2008
The DAC channel consists of optional filters for de-emphasis and bass/treble/midrange level adjustment, speaker
equalization, and 3D effects processing. The de-emphasis function is implemented by a programmable digital
filter block with fully programmable coefficients (see Page-1/Reg-21 through Page-1/Reg-26 for left channel,
Page-1/Reg-47 through Page-1/Reg-52 for right channel). If de-emphasis is not required in a particular
application, this programmable filter block can be used for some other purpose. The de-emphasis filter transfer
function is given by Equation 1 :
where the N0, N1, and D1 coefficients are fully programmable individually for each channel. The coefficients that
should be loaded to implement standard de-emphasis filters are given in Table 2 .
Table 2. De-Emphasis Coefficients for Common Audio Sampling Rates
SAMPLING FREQUENCY N0 N1 D1
32-kHz 16950 – 1220 17037
44.1-kHz 15091 – 2877 20555
48-kHz
(1)
14677 – 3283 21374
(1) Default de-emphasis coefficients
xx
In addition to the de-emphasis filter block, the DAC digital effects processing includes a fourth order digital IIR
filter with programmable coefficients (one set per channel). This filter is implemented as cascade of two biquad
sections with frequency response given by Equation 2 :
The N and D coefficients are fully programmable, and the entire filter can be enabled or bypassed. The structure
of the filtering when configured for independent channel processing is shown below in Figure 25 , with LB1
corresponding to the first left-channel biquad filter using coefficients N0, N1, N2, D1, and D2. LB2 similarly
corresponds to the second left-channel biquad filter using coefficients N3, N4, N5, D4, and D5. The RB1 and
RB2 filters refer to the first and second right-channel biquad filters, respectively.
Figure 25. Structure of the Digital Effects Processing for Independent Channel Processing
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