tda8933t-n1 NXP Semiconductors, tda8933t-n1 Datasheet - Page 27

• Manufacturer Part Number: tda8933t-n1
• Description: Tda8933 Class-d Audio Amplifier
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TDA8933_1
Preliminary data sheet
14.4 Single-ended capacitor
14.5 Gain reduction
The SE capacitor forms a high-pass filter with the speaker impedance. So the frequency
response will roll off with 20 dB per decade below f
The 3 dB cut-off frequency is equal to:
Where:
Table 15
40 Hz or 20 Hz 3 dB cut-off frequency.
Table 15.
The gain of the TDA8933 is internally fixed at 30 dB for SE, and 36 dB for BTL. The gain
can be reduced by a resistive voltage divider at the input (see
When applying a resistive divider, the total voltage gain G
Equation 8
Where:
f
G
Impedance ( )
4
6
8
–
Fig 9. Input configuration for reducing gain
v tot
f
R
C
G
G
R
3dB
3dB
L
SE
EQ
v(tot)
v(cl)
= load resistance (
=
= single-ended capacitance (F); see
= equivalent resistance, R3 and Z
= 3 dB cut-off frequency (Hz)
=
= closed-loop voltage gain, fixed at 30 dB for SE (dB)
= total voltage gain (dB)
---------------------------------- -
2
shows an overview of the required SE capacitor values in the case of 60 Hz,
G
SE capacitor values
and
v cl
R
1
L
+
Equation
20
C
log
SE
audio in
C
f
680
470
330
Rev. 01 — 15 May 2007
----------------------------------------- -
SE
R
3dB
9:
EQ
( F)
= 60 Hz
+
R
R1
EQ
+
R1
R2
R2
i
(
470 nF
470 nF
Figure
f
1000
680
470
3dB
= 40 Hz
37.
R3
3dB
(3 dB cut-off frequency).
100
k
v(tot)
010aaa137
can be calculated using
Figure
Class-D audio amplifier
f
2200
1500
1000
3dB
9).
TDA8933
© NXP B.V. 2007. All rights reserved.
= 20 Hz
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