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U2860B-B
Dual-Channel FM Sound Demodulator for TV Systems
Description
The U2860B is a dual-channel FM sound demodulator
realized with TEMIC’s advanced bipolar process. All TV
FM standards, from 4.5 up to 6.5 MHz (standard M, B/G,
I, D/K) can be processed with high performance. The
circuit is alignment-free and has a minimum number of
external components. With 5 V supply voltage, the
U2860B is suitable for TV, VCR and multimedia
applications.
Features
D Two alignment-free PLL FM demodulators,
automatic lock in on the received sound carrier
frequency
D Mono and dual channel application
D Sound IF inputs provided for ceramic filters
D Automatic mute for 2nd sound channel (squelch)
D Mute function for both sound channels
D 5 V supply voltage, low power consumption
D Few external components
Package: DIP14, SO14
VS
Cstab
13 12 11
Supply
Vin1 1
VCO 1
Loop
filter 1
8
7 VAF1
Mute 3
Mute
VCO
offset
Vin2 14
VCO 1
Loop
filter 2
Squelch 4
Squelch
Squelch (second carrier)
94 8139 e
10 VCO offset
Rref
(optional)
6 VAF2
9
Figure 1. Block diagram
TELEFUNKEN Semiconductors
Rev. A1, 17-Jun-96
Preliminary Information
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U2860B-B
Circuit Description
The U2860B includes two identical sound IF channels.
Each consists of a limiter amplifier, PLL FM demodulator
and AF amplifier. Additionally, this circuit contains a
squelch function, mute switch and internal voltage
regulation.
Limiter Amplifiers
The intercarrier signals are fed through external ceramic
bandpass filters to a 7-stage limiter amplifier. This
guarantees high input sensitivity and excellent
AM suppression.
PLL FM Demodulators
The alignment-free “Phase Locked Loop” (PLL) demo-
dulator covers a wide frequency range of 4.5 MHz up to
6.5 MHz with low noise performance. The linear voltage
to frequency characteristic results in low harmonic
distortion. The free-running frequency of the internal
VCO circuit is about 5.5 MHz. For this frequency, the
input sensitivity and VCO locking is optimal. An addi-
tional external resistor at Pin 10 allows a frequency shift
of ±1 MHz via an internal offset current. With this option,
it is possible to shift the optimum conditions to the upper
frequency (6.5 MHz) or to the lower frequency
(4.5 MHz). The offset current acts simultaneously on
both VCO circuits. If no resistor is connected, the offset
current is disabled.
Audio Amplifiers
The demodulated signals are amplified to 500 mVrms
with low output impedance at the audio outputs (Pin 6 and
Pin 7). AC decoupling at Pin 8 and Pin 9 of the audio am-
plifiers leads to high common mode rejection.
Squelch Function
For channel 2 the audio output amplifier and VCO2 is
muted automatically (squelch) when the second sound
carrier is not present. This avoids a wrong identification
for stereo and dual sound in the stereo decoder. Therefore,
with mono sound, there is no output signal at Pin 6. The
automatic squelch function can be disabled by switching
Pin 4 to ground.
Mute Switch
Simultaneously muting of both circuits is possible by
switching Pin 3 to ground.
Internal Voltage Stabilizer
The internal bandgap reference ensures constant
performance independent of supply voltage and
temperature.
Ordering Information
Extended Type Number
U2860B-B
U2860B-BFP
Package
DIP14
SO14
Remarks
taped
2 (11)
TELEFUNKEN Semiconductors
Preliminary Information
Rev. A1, 17-Jun-96

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Pin Description
Vin1 1
14 Vin2
NC 2
13 VS
Vmute 3
12 GND
Vsque 4 U2860B 11 Cstab
NC 5
10 Rref
VAF2 6
9 C9
VAF1 7
8 C8
94 8679
Figure 2. Connection diagram
U2860B-B
Pin Symbol Function
1 Vin1 Intercarrier input of sound
channel 1 (5.5 MHz)
2 NC Not connected
3 Vmute Mute for sound channel 1+2
“on/off”
4 Vsque Automatic mute for 2nd sound
channel (squelch) “on/off”
5 NC Not connected
6 VAF2 Audio output AF2 of sound
channel 2
7 VAF1 Audio output AF1 of sound
channel 1
8 C8 Decoupling capacitor for sound
channel 1
9 C9 Decoupling capacitor for sound
channel 2
10 Rref VCO offset of the free-running
frequency
11 Cstab Internal supply voltage
stabilization
12 GND Ground
13 VS Supply voltage
14 Vin2 Intercarrier input of sound
channel 2 (5.74 MHz)
Maximum Ratings
Reference point Pin 12, unless otherwise specified
Parameters
Supply voltage
Pin 13
Supply current
Pin 13
Power dissipation VS = +9 V
Output currents
Pin 6, 7
External voltages
Pin 1, 14
Pin 3, 4
Pin 6, 7, 8, 9, 10, 11
Junction temperature
Storage temperature
Electrostatic handling *) all pins
Symbol
VS
IS
P
Iout
Vext
Vext
Vext
Tj
Tstg
VESD
*) Machine model in accordance with ESD S5.2 standard
Value
9.0
33
300
±1.5
2.0
VS
4.5 V
+125
–25 to +125
±200
Unit
V
mA
mW
mA
V
V
V
°C
°C
V
TELEFUNKEN Semiconductors
Rev. A1, 17-Jun-96
Preliminary Information
3 (11)