TDA9855WP Philips Semiconductors, TDA9855WP Datasheet - Page 9

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

Philips Semiconductors
1997 Nov 04
handbook, halfpage
I
decoder and audio processor
2
C-bus controlled BTSC stereo/SAP
Fig.3 Pin configuration (SDIP version).
C DEC
OUTS
OUTL
C TW
MAD
GND
C NR
C AV
VEO
SDA
EOL
SOL
C TS
LDL
V ref
AVL
LOL
B1L
B2L
C W
VEI
C M
VIL
LIL
TL
C s
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
1
2
3
4
5
6
7
8
9
TDA9855
MHA835
52
51
50
49
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
TR
B1R
B2R
SW
n.c.
OUTR
LDR
VIR
EOR
C PS1
C PS2
LIR
AVR
SOR
LOR
C SS
C MO
CER
C ADJ
C PH
C P2
C P1
V CAP
COMP
V CC
SCL
9
FUNCTIONAL DESCRIPTION
Decoder
I
The composite input signal is fed to the input level
adjustment stage. In order to compensate tolerances of
the FM demodulator which supplied the composite input
signal, the TDA9855 provides an input level adjustment
stage. The control range is from 3.5 to +4.0 dB in steps of
0.5 dB. The subaddress control 3 of Tables 5 and 6 and
the level adjust setting of Table 22 allows an optimum
signal adjustment during the set alignment in the
production line. This value has to be stored in a
non-volatile memory. The maximum input signal voltage is
2 V (RMS).
S
The output signal of the level adjustment stage is coupled
to a low-pass filter which suppresses the baseband noise
above 125 kHz. The composite signal is then fed into a
pilot detector/pilot cancellation circuit and into the MPX
demodulator. The main L + R signal passes a 75 s fixed
de-emphasis filter and is fed into the dematrix circuit.
The decoded sub-signal L
switch. To generate the pilot signal the stereo demodulator
uses a PLL circuit including a ceramic resonator.
The stereo channel separation can be adjusted by an
automatic procedure or manually. For a detailed
description see Section “Adjustment procedure”.
The stereo identification can be read by the I
(see Table 2). Two different pilot thresholds can be
selected via the I
SAP
The composite signal is fed from the output of the input
level adjustment stage to the SAP demodulator circuit
through a 5f
The demodulator level is automatically controlled.
The SAP demodulator includes internal noise and field
strength detectors that mute the SAP output in the event of
insufficient signal conditions. The SAP identification signal
can be read by the I
S
The stereo/SAP switch feeds either the L
SAP demodulator output signal via the internal dbx noise
reduction circuit to the dematrix/line out select circuit.
Table 21 shows the different switch modes provided at the
output pins LOR and LOL.
NPUT LEVEL ADJUSTMENT
TEREO DECODER
WITCH
DEMODULATOR
H
(f
H
2
= horizontal frequency) band-pass filter.
C-bus (see Table 24).
2
C-bus (see Table 2).
R is sent to the stereo/SAP
Product specification
TDA9855
R signal or the
2
C-bus