Features
•
•
•
•
•
•
•
Completely Alignment-free
PLL Demodulator for FM Intercarrier Sound IF Signals (Mono)
Two Audio Switches
Very Few External Components
Volume Control by DC Voltage
Supply Voltage: 5V
Pb-free Package, which is Compliant with Requirements of RoHS
Mono FM Sound
Demodulator for
TV Systems
U2861B
1. Description
The U2861B is an alignment-free FM sound IF demodulator for all TV standards from
4.5 MHz up to 6.5 MHz (standard M, N, B/G, I, D/K). The circuit includes two switch-
able audio inputs and volume control. With a supply voltage of 5V, the U2861B is
suitable for TV, VCR and Multimedia applications.
Figure 1-1.
Block Diagram
AF1IN
AF1OUT
AF2IN
VS
VI,AF1
1
VO,AF1
12
VI,AF2
10
CREF
6
VS
7
Bandgap
reference
VCO
Switch2
Sound IF
input
3
VI,SIF
4
GND
2
CDEC
5
VMUTE
Switch1
5 kΩ
8 VO,AF2
AF2OUT
14
CDEM
13
VSW1
11
VSW2
9
VVOl
Decoupling
FM
mute
De-
emphasis
Audio
switch1
Audio
switch2
Volume
control
Rev. 4798B–TVVCR–07/05
2. Circuit Description
Sound IF Limiter Amplifier
The intercarrier signal coming from the sound filter is fed to a 7-stage limiter amplifier. This guar-
antees high input sensitivity and excellent AM suppression.
2.1
PLL - FM Demodulator
The alignment-free “Phase-Locked-Loop” (PLL) FM demodulator covers a wide frequency range
of 4.5 MHz up to 6.5 MHz with excellent noise performance.
Due to the fact that the voltage-to-frequency characteristic is linear, a low harmonic distortion
can be achieved. The free-running frequency of the internal VCO circuit is about 5.5 MHz.
The demodulated FM signal is led via de-emphasis and buffered to pin 12. The de-emphasis
low-pass filter consists of an internal 5-kΩ series resistor and an external capacitor at pin 14.
The FM muting is possible by switching pin 5 to ground.
2.2
Audio Switch 1
The first audio switch (pin 13) has inputs for the demodulated FM signal and the external AF1
signal from pin 1.
For multistandard purposes, it is possible to handle internal FM and external AM audio signals.
The output of switch1 is also permanently available at pin 12 (e.g., for SCART interface).
2.3
Audio Switch 2 and Volume Control
The second audio switch (pin 11) has inputs for the audio signal from switch 1 and the external
AF2 signal at pin 10. The switched AF signal is fed to volume control. The output voltage can be
controlled by a DC voltage at pin 9.
2.4
Internal Voltage Stabilizer
The internal band-gap reference ensures constant performance independent of supply voltage
and temperature.
2
U2861B [Preliminary]
4798B–TVVCR–07/05
U2861B [Preliminary]
3. Pin Configuration
Figure 3-1.
Pinning
VI,AF1
CDEC
VI,AF1
1
2
3
14 CDEM
13 VSW1
12 VO,AF1
GND
VMUTE
4
5
U2861B
11 VSW2
10 VI,AF2
9
8
VVOl
CREF
VS
6
7
VO,AF2
Table 3-1.
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Pin Description
Symbol
VI,AF1
CDEC
VI,SIF
GND
VMUTE
CREF
VS
VO,AF2
VVOL
VI,AF2
VSW2
VO,AF1
VSW1
CDEM
Function
Audio input 1 (e.g., AM signal)
Decoupling capacitor
FM sound IF input
Ground
FM mute switch
Internal reference voltage
Supply voltage
Switched audio output 2
Volume control
Audio input 2 (e.g., from SCART)
Audio switch 2
Switched audio output 1
Audio switch 1
De-emphasis and mute switch
3
4798B–TVVCR–07/05
4. Absolute Maximum Ratings
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating
only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this
specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Reference point pin 4, unless otherwise specified.
Parameters
Supply voltage
SO14 package
Supply current
Power dissipation
V
S
= 6 V
Output currents
External voltages
Junction temperature
Storage temperature
Electrostatic handling
(1)
Note:
All
8, 12
1, 2, 3, 5, 6, 8, 9,
10, 12, 13, 14
11
T
j
T
stg
V
ESD
Pin
7
7
Symbol
V
S
I
S
P
I
out
V
ext
Value
6.0
25
150
1.0
+4.5
+12.0
+125
–25 to +125
±200
Unit
V
mA
mW
mA
V
V
°C
°C
V
1. Equivalent to discharging a 200-pF capacitor through a 0-Ω resistor
5. Thermal Resistance
Parameters
Junction ambient when soldered to PCB
SO14 package
Symbol
R
thJA
Value
140
Unit
K/W
4
U2861B [Preliminary]
4798B–TVVCR–07/05
U2861B [Preliminary]
6. Electrical Characteristics
V
S
= +5V, T
amb
= +25°C; reference point pin 4, unless otherwise specified.
Parameters
DC Supply (Pin 7)
Supply voltage
SO14 package
Supply current
FM Sound IF Input (Pin 3)
Input limiting voltage, RMS value
DC input voltage
Input resistance
Input capacitance
FM - PLL
Free-running frequency
Oscillator drift (free running) as
function of temperature
Oscillator shift (free running) as
function of supply voltage
Capture range of PLL
Holding range of PLL
Decoupling Capacitor (Pin 2)
Value of decoupling capacitor
De-emphasis Capacitor (Pin 14)
Value of de-emphasis capacitor
Audio Output 2 (Pin 8)
DC output voltage
Output resistance
AC output peak current
DC output current
AF output voltage, RMS value
V
in
= 10 mV, f = 5.5 MHz
FM-deviation = 27 kHz
f
mod
= 1 kHz
V
in
= 10 mV, f = 5.5 MHz
FM-deviation = 27 kHz
f
mod
= 1 kHz
V
in
= 10 mV, f = 5.5 MHz, f
mod
=1 kHz
Reference signal: FM-deviation = 27 kHz
Test signal: m = 30%
V
RR
< 200 mV, f = 70 Hz
V
DC
R
out
I
AC
I
DC
V
o,AF2
500
2.2
130
±1.0
–1.2
V
Ω
mA
mA
mV
RMS
τ
= 50 µs
C
dem
10
nF
C
dec
2.2
µF
∆T
= 55°C
4.5 V < V
s
< V
S,max
f
vco
∆f
vco
∆f
vco
∆f
cap
∆f
hold
±1.4
±2.0
5.5
500
200
±1.9
±2.5
MHz
kHz
kHz
MHz
MHz
(1)
(1)
AF output signal at pin 8 and pin12: –3 dB
V
i,SIF
V
DC
R
in
C
in
1.7
600
1.5
750
150
µV
RMS
V
Ω
pF
V
S
I
S
4.5
5.0
20
6.0
25
V
mA
Test Conditions
Symbol
Min.
Typ.
Max.
Unit
Total harmonic distortion
THD
0.1
0.5
%
AM suppression
Supply voltage ripple rejection
Notes:
a
AM
RR
42
60
30
dB
dB
1. This parameter is given as application information and is not tested during production.
2. Without external control voltage at pin 13, the internal FM is demodulated.
3. Without control voltage at pin 11, the audio signal from switch 1 is automatically selected.
With V11 < 1.5 or V11 > 4.0V input pin 10 is selected.
5
4798B–TVVCR–07/05
