TFA9812HN PHILIPS [NXP Semiconductors], TFA9812HN Datasheet - Page 18

• Manufacturer Part Number: TFA9812HN
• Description: BTL stereo Class-D audio amplifier with I2S input
• Manufacturer: PHILIPS [NXP Semiconductors]

NXP Semiconductors
TFA9812_2
Preliminary data sheet
8.5.1.3 Equalizer band control
The ranges of the TFA9812 parametric equalizer settings for each band are:
Using I
as desired.
Figure
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
control the actual configuration and should be chosen according to
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
scale signal processing safeguards. Band filters can be scaled with the binary parameters
listed in
Table 14.
For compact representation with positive signed parameters, parameters k
introduced in
The parameters k
word1 and word2, and must fit within the representation given in
and k
K
t
s
0
1
1
6 dB amplification should be applied to the highest possible sections that are still within
t
•
•
•
2
2
=
=
The Gain, G is from 30 dB to +12 dB.
The center frequency, f
The quality factor Q is from 0.001 to 8.
=
2
0
1
' are unsigned floating-point representations in
2
6,
2Q
1
0
C control, filter coefficients need to be entered for each filter stage to configure it
Table
K
Figure 7
–
Equalizer scale factor coding
1
K
sin
=
0
Equation
k
k
14.
<=
>
2
=
2
–
<0
>=0
cos
0
G
and
, k
2
2
2Q
1
Rev. 02 — 22 January 2009
', k
Figure 8
7.
+
2
sin
', t
c
1
is from 0.0004 * f
, t
2
G 1
show some of the possible transfer functions of the
and s must be combined in two 16-bit control words,
BTL stereo Class-D audio amplifier with I
scale factor (dB)
0
s
6
to 0.49 * f
Equation
s
.
8.
Table
Equation
15. Parameters k
© NXP B.V. 2009. All rights reserved.
TFA9812
1
’ and k
6.
2
1
S input
2
18 of 66
’ are
and t
(5)
(6)
1
2
'