U2841B
Preliminary Information
TELEFUNKEN Semiconductors
Rev. A1, 17-Jul-96
1 (9)
Monolithic Integrated Circuit
Description
The integrated circuit, U2841B, is designed as a single
FM-IF-amplifier and demodulator for TV sound
processing with SCART switches and AF control in
bipolar technology.
Features
D IF input provided for operating with ceramic filters
D Minimum total harmonic distortion
D Low power consumption
D Operates alternatively with 5 V or 12 V
supply voltage
D Demodulator provided for operating with
ceramic resonator or coil
D SCART AF input / AF output
D Wide volume control range
D ESD protected
Block Diagram
V
stab2
V
stab1
G=2
G=1
V
S
< 6 V
V
S
> 7 V
2.4 V / 3.7 V
9
10
12
AF input
demod. signal
SCART
AF input
SCART
AF output
5
6
7
11 k
W
4
47 pF
47 pF
Tuned
reference circuit
8
4.7 nF
Deemphasis
2
16
15
3
+V
S
Mute control
voltage
IF input
1
14
AF output (controlled)
13
11
Volume control
SCART switch
93 7519
Figure 1.
U2841B
TELEFUNKEN Semiconductors
Rev. A1, 17-Jul-96
Preliminary Information
2 (9)
Pin Description
GND
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
V
MUTE
C
3
V
out
95 11253
V
out
V
in
V
in
C
de
V
out, AF
V
13
V
in, AF (SCART)
V
SW
V
in, AF
V
out, AF (SCART)
V
in, IF
V
S
Pin
Symbol
Function
1
GND
Ground
2
V
MUTE
Mute control voltage
3
C
3
Capacitor
(internal reference voltage)
4, 5
V
out
Limiter amplifier output
6, 7
V
in
Reference circuit
(demodulator)
8
C
de
Deemphasis
9
V
out, AF (SCART)
AF output (SCART)
10
V
in, AF
AF input
(demodulated signal)
11
V
SW
SCART switch
12
V
in, AF (SCART)
AF input (SCART)
13
V
13
Volume control
14
V
out, AF
AF output, controlled
15
V
S
Supply voltage
16
V
in, IF
FM IF input
Circuit Description
The bipolar circuit U2841B contains the complete FM
intercarrier sound processing (mono) with additional AF
volume control, SCART switches and external mute
control. The circuit operates alternatively with 5 V or
12 V supply voltage.
Circuit operation is as follows:
Through an external ceramic bandpass filter, which is
tuned to the sound carrier frequency, the intercarrier
signal is fed via a 9-stage limiting amplifier to the FM
demodulator. This quadrature demodulator works
alternatively with an external L-C reference circuit or
with a ceramic resonator.
The AF signal is available at Pin 9 (AF output
*SCART),
and via the SCART switch and volume control at Pin 14
(AF output
*controlled). The demodulated AF signal at
Pin 10 (AF input
*demodulator signal) or an external
signal at Pin 12 (AF input
*SCART) will be selected by
the SCART switch and supplied to the volume control.
In dependence on supply voltage the gain of controlled
AF output (Pin 14) will be switched over:
a)
Supply voltage range 4.7 < V
S
< 6.0 V:
gain of AF output amplifier G = 2.
In this case the AF input signal at Pin 12
(SCART input) must be reduced by an voltage
divider.
b) Supply voltage range 7.0 < V
S
< 12.5 V:
gain of AF output amplifier G = 1.
U2841B
Preliminary Information
TELEFUNKEN Semiconductors
Rev. A1, 17-Jul-96
3 (9)
Absolute Maximum Ratings
Reference point Pin 1, unless otherwise specified
Parameters
Symbol
Value
Unit
Supply voltage
Pin 15
V
S
12.5
V
Supply current
Pin 15
I
S
33
mA
External voltage
Pins 2, 3, 4, 5, 7, 8, 9, 10, 12,
13, 14 and 16
V
ext
5
V
External voltage
Pin 11
V
ext
V
S
V
Junction temperature
T
j
125
C
Ambient temperature
T
amb
25 to +85
C
Storage temperature
T
stg
25 to +125
C
Thermal Resistance
Parameters
Symbol
Value
Unit
Junction ambient
R
thJA
90
K/W
Electrical Characteristics
T
amb
= 25
C, V
S
= 12 V, reference point Pin 1, unless otherwise specified
Parameters
Test Conditions / Pins
Symbol
Min
Typ
Max
Unit
Supply voltage
Pin 15
V
S
4.7
7.0
6.0
12.5
V
Supply current
V
S
t 6 V
Pin 15
V
S
u 7 V
I
S
22
28
mA
IF frequency range
Pin 16
f
IF
3.5
12
MHz
DC output voltage
V
S
t 6 V
Pins 9 and 14
V
S
u 7 V
V
DC
2.4
3.7
V
AF output voltage
f
mod
+1 kHz Pins 9 and 14
D
f
+ "30 kHz
V
AF
600
mV
Total harmonic distortion
f
mod
+1 kHz
Pins 9 and 14
D
f
+ "30 kHz
T
HD
0.5
%
Input limiting voltage
AF output sign 3 dB
Pin 16
V
in
150
mV
eff
AM suppression
V
in
+
20 mV, Pins 4 and 5
f
+ 5.5 MHz
f
mod
+ 1 kHz
Reference signal:
D
f
+"30 kHz
Test signal: m
+30%
G
AM
60
dB
Input resistance
Pin 16
R
in
820
W
Allowable external load
resistor, AF
output
Pins 9 and 14
R
L
3
k
W
Control range
AF
volume control
V
13
+0 *4 V
Pin 14
A
80
dB
Gain between SCART input
and controlled AF output
V
S
t 6 V
Pins 12 14
V
S
u 7 V
G
6
0
dB
U2841B
TELEFUNKEN Semiconductors
Rev. A1, 17-Jul-96
Preliminary Information
4 (9)
Unit
Max
Typ
Min
Symbol
Test Conditions / Pins
Parameters
Max. SCART input voltage
V
S
t 6 V
Pins 10
and 12
V
S
u 7 V
V
in max
1
2
V
eff
Max. AF output voltage
V
S
t 6 V
Pins 10
and 12
V
13
+4 V
V
AF max
1
2
V
eff
(controlled output)
V
S
u 7 V
2
Control voltage
Record
Pin 11
V
0
2
V
(SCART switch)
Play
Pin 11
4
V
S
Control voltage
Mute on
Pin 2
V
0
2
V
(MUTE switch)
Circuits
16
15
14
13
1
2
3
4
U2841B
12
11
10
5
6
7
9
8
22 nF
2.2
mF
22
mF
SFE 5.5 MC
IF input
Volume
control
+V
S
AF output
(controlled)
V
S
< 6 V V
S
> 7 V
AF input SCART
SCART
switch
300
W
2.2
mF
1
mF
2.2
mF
V
S
< 6 V
V
S
> 7 V
AF output
SCART
82 pF
2.2
mF
270
W
CDA 5.5 MC
4.7 nF
Reference circuit
(demodulator)
Mute switch
937520
Deemphasis
36 k
W
Figure 2. Test circuit
U2841B
Preliminary Information
TELEFUNKEN Semiconductors
Rev. A1, 17-Jul-96
5 (9)
Internal Pin Circuit Diagrams
2
20 k
W
3.4 V
93 7509
Figure 3. Pin 2: Mute switch
4.1 V
3
93 7510
Figure 4. Pin 3: Internal reference voltage
4
93 7511
5
1.8
k
W
1.8 k
W
Figure 5. Pin 4, 5: Limiter amplifier output
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