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TFA9812_2 © NXP B.V. 2009. All rights reserved.
Preliminary data sheet Rev. 02 — 22 January 2009 19 of 66
NXP Semiconductors
TFA9812
BTL stereo Class-D audio amplifier with I
2
S input
(7)
(8)
In Equation 8, M is the unsigned mantissa and E the negative signed exponent. For
example, in word2 bits [14:8] = [0111 010] represent k
2
' = (7/2
4
) × 2
−2
= 1.09375 10
−1
.
Section 9.5.4 shows the I
2
C address locations of the controls for various bands of the
equalizer.
Table 15. Equalizer control word construction
Word Section Data
word1 15 t
1
word1 [14:4] 11 mantissa bits of k
1
’
word1 [3:0] Four exponent bits of k
1
’
word2 15 t
2
word2 [14:11] Four mantissa bits of k
2
’
word2 [10:8] Three exponents bits of k
2
’
word2 [7:1] k
0
word2 0 s
Fig 6. Transfer functions for several quality factors Q
k
1
′
1k
1
– t
1
1=
1k
1
+ t
1
0=
=
k
2
′
1k
2
– t
2
0=
1k
2
+ t
2
1=
=
k
x
M2
E–
⋅
M1<
=
010aaa222
4
8
12
Gain
(dB)
0
Frequency (Hz)
10
1
10
5
10
4
10
2
10
3
Q1 = 0.27
Q2 = 0.61
Q3 = 1.65