U2841B Datasheet, PDF (2/9 Pages) TEMIC Semiconductors – Monolithic Integrated Circuit

U2841B
Pin Description
GND 1
V_MUTE 2
C₃
3
V_out
4
V_out 5
V_in
6
V_in
7
C_de
8
16 V_{in, IF}
15 V_S
14 ^Vout, AF
13 ^V13
12 Vin, AF (SCART)
11 V_SW
10 ^Vin, AF
95 11253
9 ^Vout, AF (SCART)
Pin
Symbol Function
1
GND
Ground
2
V_MUTE
Mute control voltage
3
C₃
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
V₁₃
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.
2 (9)
TELEFUNKEN Semiconductors
Preliminary Information
Rev. A1, 17-Jul-96