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TFA9812HN/N1,518

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P36P37-P39P40-P42P43-P45P46-P48P49-P51P52-P54P55-P57P58-P60P61-P63P64-P66
TFA9812_2 © NXP B.V. 2009. All rights reserved.
Preliminary data sheet Rev. 02 — 22 January 2009 16 of 66
NXP Semiconductors
TFA9812
BTL stereo Class-D audio amplifier with I
2
S input
In I
2
C control mode the following sample frequency f
s
can be used: 8 kHz, 11.025 kHz,
12 kHz, 16 kHz, 22.05 kHz, 24 kHz, 32 kHz, 44.1 kHz, 48 kHz, 64 kHz, 88.2 kHz, 96 kHz,
128 kHz, 176.4 kHz or 192 kHz. The I
2
C control for f
s
selection can be found in
Section 9.5.7.
In Legacy control mode the following sample frequencies (f
s
) can be used: 32 kHz,
44.1 kHz or 48 kHz.
8.4.2 Digital audio data format control
The BCK-to-WS and MCLK-to-WS frequency ratios are automatically detected, so no
control settings need to be configured for these.
In I
2
C control mode all the formats listed in Table 12 are supported. The appropriate I
2
C
controls for selecting the supported formats can be found in Section 9. In the Legacy
control mode only a subset of the supported formats can be used. These are shown in
Table 12 and the required pin control is given in Table 13.
See Section 8.2.1 for details of how to enable Legacy control mode.
8.5 Digital signal-processing features
8.5.1 Equalizer
8.5.1.1 Equalizer options
The equalizer function can be bypassed and the equalizer can be configured to either a
5-band or 10-band function. These settings are for both audio channels simultaneously.
There are 20 bands in the equalizer. These are distributed as follows:
• Bands A1 to A5 are bands 1 to 5 of output 1 (used in 5-band and 10-band
configuration).
• Bands B1 to B5 are bands 1 to 5 of output 2 (used in 5-band and 10-band
configuration).
• Bands C1 to C5 are bands 6 to 10 of output 1 (used in 10-band configuration only).
• Bands D1 to D5 are bands 6 to 10 of output 2 (used in 10-band configuration only).
In I
2
C control mode each band can be configured separately using I
2
C register settings.
In Legacy control mode the equalizer is bypassed.
8.5.1.2 Equalizer band function
The shape of each parametric equalizer band is determined by the three filter parameters:
• (Relative) center frequency .
• Quality factor Q.
• Gain factor G.
Table 13. Digital audio data format selection in Legacy control mode
SCL/SFOR pin value Interface formats (MSB-first)
0I
2
S
1 MSB-justified
ω 2π f
c
f
s
⁄()=
TFA9812_2 © NXP B.V. 2009. All rights reserved.
Preliminary data sheet Rev. 02 — 22 January 2009 17 of 66
NXP Semiconductors
TFA9812
BTL stereo Class-D audio amplifier with I
2
S input
In the above equation f
c
is the center frequency and f
s
is the sample frequency.
The definition of the quality factor is the center frequency divided by the 3 dB bandwidth,
see Equation 1. In parametric equalizers this is only valid when the gain is set very small
(−30 dB).
(1)
Each band filter can be programmed to perform a band-suppression (G < 1) or a
band-amplification (G > 1) function around the center frequency.
Each band of the TFA9812 equalizer has a second-order Regalia-Mitra all-pass filter
structure. The structure is shown in Figure 5.
The transfer function of this all-pass filter is shown in Equation 2:
(2)
A(z) is the second-order filter structure. The transfer function of A(z) is shown in
Equation 3:
(3)
The relationship between the programmable parameters K
0
, K
1
, and K
2
and the filter
parameters G, ω, Q is shown in Equation 4 and Equation 5.
Use Equation 4 to calculate band suppression (G < 1) functions.
(4)
Use Equation 5 to calculate band amplification (G ≥ 1) functions.
Fig 5. Regalia filter flow-diagram
Q
f
c
f
2
f
1
–
-----------------
;=
f
1
: 20
10
A
f
1
A
f
c
--------



log 3dB f
c
f
1
>=
f
2
: 20
10
A
f
2
A
f
c
--------



log 3dB f
2
f
c
>,=
½
X(z)
A(z)
s
Y(z)
+
+
+
−
010aaa406
K
0
/2
Hz() 12⁄ 1Az()+()K
0
2⁄ 1Az()–()⋅+⋅=
Az()
K
1
K
2
1K
1
+()Z
1–
Z
2–
+⋅⋅+
1K
2
1K
1
+()Z
1–
K
1
Z
2–
⋅+⋅⋅+
---------------------------------------------------------------------------------
=
K
0
G=
K
1
ωcos–=
K
2
2Q G ωsin–⋅()2Q G ωsin+⋅()⁄=
G1<
TFA9812_2 © NXP B.V. 2009. All rights reserved.
Preliminary data sheet Rev. 02 — 22 January 2009 18 of 66
NXP Semiconductors
TFA9812
BTL stereo Class-D audio amplifier with I
2
S input
(5)
The ranges of the TFA9812 parametric equalizer settings for each band are:
• The Gain, G is from −30 dB to +12 dB.
• The center frequency, f
c
is from 0.0004 * f
s
to 0.49 * f
s
.
• The quality factor Q is from 0.001 to 8.
Using I
2
C control, filter coefficients need to be entered for each filter stage to configure it
as desired.
Figure 6, Figure 7 and Figure 8 show some of the possible transfer functions of the
equalizer bands. The relations are symmetrical for the suppression and amplification
functions. A skewing effect can be observed for the higher frequencies.
Different configurations are available for the same filter transfer function, thus allowing
optimum numerical noise performance. The binary filter configuration parameters t
1
and t
2
control the actual configuration and should be chosen according to Equation 6.
(6)
A maximum of 12 dB amplification per equalizer stage can be achieved with respect to the
input signal. Each band of the equalizer is provided with a −6 dB amplification, so in order
to prevent numerical clipping for some filter settings with over 6 dB of amplification, band
filters can be scaled by 0 dB or −6 dB. For optimum numerical noise performance steps of
−6 dB amplification should be applied to the highest possible sections that are still within
scale signal processing safeguards. Band filters can be scaled with the binary parameters
listed in Table 14.
8.5.1.3 Equalizer band control
For compact representation with positive signed parameters, parameters k
1
’ and k
2
’ are
introduced in Equation 7.
The parameters k
0
, k
1
', k
2
', t
1
, t
2
and s must be combined in two 16-bit control words,
word1 and word2, and must fit within the representation given in Table 15. Parameters k
1
'
and k
2
' are unsigned floating-point representations in Equation 8.
Table 14. Equalizer scale factor coding
s scale factor (dB)
00
1 −6
K
0
G=
K
1
ωcos–=
K
2
2Q ωsin–()2Q ωsin+()⁄=
G1≥
t
1
0 ω<=π 2⁄
1 ω>π 2⁄
=
t
2
0k
2
>=0
1k
2
<0
=
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P36P37-P39P40-P42P43-P45P46-P48P49-P51P52-P54P55-P57P58-P60P61-P63P64-P66

TFA9812HN/N1,518

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Manufacturer:
NXP Semiconductors
Description:
IC AMP AUDIO 15W STER D 48HVQFN
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