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Monolithic Integrated Circuit
U2841B
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
47 pF
47 pF
Tuned
reference circuit
IF input
93 7519
16
456
7
Mute control 2
voltage
3
2.4 V / 3.7 V
V >7V
G=1 S
+VS 15
Vstab1
Vstab2
G=2
VS < 6 V
1 14
13
AF output (controlled)
Volume control
Figure 1.
Deemphasis
4.7 nF
8
11 kW
SCART
9 AF output
11
SCART switch
10
AF input
12 demod. signal
SCART
AF input
TELEFUNKEN Semiconductors
Rev. A1, 17-Jul-96
Preliminary Information
1 (9)

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U2841B
Pin Description
GND 1
VMUTE 2
C3 3
Vout 4
Vout 5
Vin 6
Vin 7
Cde 8
16 Vin, IF
15 VS
14 Vout, AF
13 V13
12 Vin, AF (SCART)
11 VSW
10 Vin, AF
95 11253
9 Vout, AF (SCART)
Pin Symbol Function
1
GND
Ground
2
VMUTE
Mute control voltage
3 C3 Capacitor
(internal reference voltage)
4, 5 Vout Limiter amplifier output
6, 7 Vin Reference circuit
(demodulator)
8 Cde Deemphasis
9 Vout, AF (SCART) AF output (SCART)
10
Vin, AF
AF input
(demodulated signal)
11
VSW
SCART switch
12 Vin, AF (SCART) AF input (SCART)
13 V13 Volume control
14
Vout, AF
AF output, controlled
15 VS Supply voltage
16
Vin, 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 < VS < 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 < VS < 12.5 V:
gain of AF output amplifier G = 1.
2 (9) TELEFUNKEN Semiconductors
Preliminary Information
Rev. A1, 17-Jul-96

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U2841B
Absolute Maximum Ratings
Reference point Pin 1, unless otherwise specified
Supply voltage
Supply current
External voltage
External voltage
Junction temperature
Ambient temperature
Storage temperature
Parameters
Pin 15
Pin 15
Pins 2, 3, 4, 5, 7, 8, 9, 10, 12,
13, 14 and 16
Pin 11
Symbol
VS
IS
Vext
Vext
Tj
Tamb
Tstg
Value
12.5
33
5
VS
125
–25 to +85
–25 to +125
Unit
V
mA
V
V
°C
°C
°C
Thermal Resistance
Junction ambient
Parameters
Symbol
RthJA
Value
90
Unit
K/W
Electrical Characteristics
Tamb = 25°C, VS = 12 V, reference point Pin 1, unless otherwise specified
Parameters
Test Conditions / Pins Symbol Min Typ Max Unit
Supply voltage
Supply current
tVS 6 V
uVS 7 V
Pin 15
Pin 15
VS 4.7
7.0
6.0 V
12.5
IS 22 mA
28
IF frequency range
Pin 16
fIF 3.5
12 MHz
tuDC output voltage
VS 6 V Pins 9 and 14
VS 7 V
VDC
2.4
3.7
V
++"AF output voltage
fDmfod
1 kHz Pins 9 and 14
30 kHz
VAF
600
mV
++"Total harmonic distortion
fDmfod
1 kHz Pins 9 and 14
30 kHz
THD
0.5
%
Input limiting voltage
AF output sign –3 dB
Pin 16
Vin
150 mVeff
++AM suppression
Vin 20 mV, Pins 4 and 5
f 5.5 MHz
GAM
60
dB
+fmod 1 kHz
Reference signal:
+"Df 30 kHz
+Test signal: m 30%
Input resistance
Pin 16
Rin
820
Allowable external load
Pins 9 and 14 RL
3
resistor, AF output
Control range
+ *V13 0 4 V
A
80
AF volume control
tGain between SCART input VS
uand controlled AF output VS
6V
7V
Pin 14
Pins 12 – 14
G
6
0
W
kW
dB
dB
TELEFUNKEN Semiconductors
Rev. A1, 17-Jul-96
Preliminary Information
3 (9)