TDA9855WP Philips Semiconductors, TDA9855WP Datasheet - Page 38

• Manufacturer Part Number: TDA9855WP
• Description: I2C-bus controlled BTSC stereo/SAP decoder and audio processor
• Manufacturer: Philips Semiconductors

Philips Semiconductors
Loudness filter calculation example
Figure 12 shows the basic loudness circuit with an
external low-pass filter application. R1 allows an
attenuation range of 21 dB while the boost is determined
by the gain stage V
range of +16 to 12 dB.
Defining f
change while switching loudness on/off. The external
resistor R3 for f
R3 = 3.2 k is generated.
For the low-pass filter characteristic the value of the
external capacitor C1 can be determined by setting a
specific boost for a defined frequency and referring the
gain to G
For example: 3 dB boost at f = 1 kHz
G
If a loudness characteristic with additional high frequency
boost is desired, an additional high-pass section has to be
included in the external filter circuit as indicated in the
block diagram. A filter configuration that provides
AC coupling avoids offset voltage problems.
Figure 13 shows an example of the loudness circuit with
bass and treble boost.
1997 Nov 04
R3
-------------------- -
j
v
I
decoder and audio processor
= G
2
1
=
C1
C-bus controlled BTSC stereo/SAP
R1
v(ref)
v
ref
-------------------- -
1 10
at f
=
+ 3 dB = 18 dB; f = 1 kHz and C1 = 100 nF.
10
–
as the frequency where the level does not
------------------------------------------------------------- -
ref
R1
G
------ -
20
ref
v
G
------ -
20
as indicated above.
v
+
. With G
1
R3
. Both result in a loudness control
1 10
–
can be calculated as:
10
G
------ -
20
v
v
= 21 dB and R1 = 33 k ,
G
------ -
20
v
–
R3
38
handbook, halfpage
handbook, halfpage
Fig.13 Loudness circuit with bass and treble boost.
C KVL
20 k
8.2 nF
220 nF
Fig.12 Basic loudness circuit.
R3
C1
LOX
VIX
2.2 k
150
nF
LOX
VIX
33 k
R1
33 k
R1
Product specification
V 1
V 1
TDA9855
MHA838
R2
MHA839
R2