TFA9879 NXP Semiconductors, TFA9879 Datasheet - Page 14

• Manufacturer Part Number: TFA9879
• Description: The TFA9879 contains a processor that supports a range of sound processing featuresincluding a 5-band parametric equalizer, separate bass and treble control, a dynamicrange compressor, soft clip control and volume control
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TFA9879
Product data sheet
9.2.5.2 Equalizer band control
For optimum numerical noise performance, different configurations are available for a
given filter transfer function. The binary filter configuration parameters t
actual configuration and should be chosen according to
A maximum of 12 dB amplification, with respect to the input signal, can be achieved per
equalizer stage. The equalizer band signals are processed in sequence, from the highest
(Band A) to the lowest (Band E). Each band can attenuate the signal by 6 dB so, in order
to prevent numerical clipping at filter settings of over 6 dB 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 bands in sequence, starting with B and A, as long as
they are able to amplify the signal without clipping.
A filter scale factor, s, is associated with each of the equalizer bands and is set via the
relevant EQx_s control bit (see
Table 7.
For compact representation with positive signed parameters, parameters k
introduced in
Parameters K
and word2 (see
and k
In
example, in word2 bits [14:8] = [0111 010] represent k
t
t
k
k
k
k
s
0
1
1
2
0
1
2
x
′
′
′
′
Equation
=
=
=
=
=
=
⎛
⎜
⎝
⎛
⎜
⎝
1
1
2
0
0
K
⎛
⎜
⎝
⎛
⎜
⎝
M 2
' are unsigned floating-point representations in
1
1
1 K
1 K
0
⋅
+
+
–
–
Equalizer filter scale factor settings
K
K
–
K
E
9, M is the unsigned mantissa and E the negative signed exponent. For
K
K
K
1
1
2
2
2
Equation
2
0
M 1
1
1
, k
<
≥
>
<
≤
All information provided in this document is subject to legal disclaimers.
Table 24
0
0
0
1
0
', k
t
t
t
t
1
2
1
2
2
=
=
=
=
', t
Rev. 02 — 15 October 2010
8.
0
0
1
1
1
and
, t
2
and s must be combined in two 16-bit control words, word1
Table
Table
Mono BTL class-D audio amplifier with digital input
25), using the format shown in
25).
scale factor (dB)
0
−6
Equation
2
' = (7/2
Equation
4
) × 2
8.
7.
Table
−2
= 1.09375 × 10
1
TFA9879
© NXP B.V. 2010. All rights reserved.
8. Parameters k
and t
1
’ and k
2
control the
2
14 of 60
’ are
−1
.
(7)
(8)
(9)
1
'