TDA4472-M

Preliminary Information

TELEFUNKEN Semiconductors
Rev. A2, 15-Oct-96

1 (14)

Video-IF and Quasi Parallel Sound Processing

Description

The TDA4472 is an integrated bipolar circuit for video/
sound IF (VIF/SIF) signal processing in TV/VCR and
multimedia applications. The circuit processes all TV

video IF signals with negative modulation (e.g., B/G
standard), and the FM/NICAM sound IF signals.

Features

D 5 V supply voltage; low power consumption

D Active carrier generation by FPLL principle

(frequency-phase-locked-loop) for true
synchronous demodulation

D Very linear video demodulation, good pulse response

and excellent intermodulation figures

D VCO circuit operates at picture carrier frequency

D Alignment-free AFC without external reference

circuit, polarity of the AFC curve is switchable

D VIF-AGC with peak sync. detection

D Tuner AGC with adjustable take over point

D Alignment-free quasi parallel sound (QPS) mixer for

FM/NICAM sound IF signals

D Intercarrier output signal is gain controlled (necessary

for digital sound processing)

D Separate SIF-AGC with average detection
D Two independent SIF inputs
D Package and relevant pinning is compatible with the

multistandard version TDA4470, which simplifies the
design of an universal IF module

Package: SDIP28, SO28

Ordering Information

Extended Type Number

Package

Remarks

TDA4472-MSD

SDIP28

TDA4472-MFLG3

SO28

Delivery in taped form

TDA4472-M

Preliminary Information

TELEFUNKEN Semiconductors
Rev. A2, 15-Oct-96

3 (14)

Circuit Description

Vision IF Amplifier

The video IF signal (VIF) is fed through a SAW filter to
the differential input (Pin 6-7) of the VIF amplifier. This
amplifier consists of three AC-coupled amplifier stages.
Each differential amplifier is gain controlled by the auto-
matic gain control (VIF-AGC). The output signal of the
VIF amplifier is applied to the FPLL carrier generation
and the video demodulator.

Tuner-and VIF-AGC

At Pin 8, the VIF-AGC charges/discharges the AGC
capacitor to generate a control voltage for setting the gain
of the VIF amplifier and tuner in order to keep the video
output signal at a constant level. Therefore, in the case of
all negative modulated signals (e.g., B/G standard) the
sync. level of the demodulated video signal is the
criterion for a fast charge/discharge of the AGC capacitor.
The control voltage (AGC voltage at Pin 8) is transferred
to an internal control signal, and is fed to the tuner AGC
to generate the tuner AGC current at Pin 11 (open
collector output). The take over point of the tuner AGC
can be adjusted at Pin 10 by a potentiometer or an external
dc voltage (from interface circuit or microprocessor).

FPLL, VCO and AFC

The FPLL circuit (frequency phase locked loop) consists
of a frequency and phase detector to generate the control
voltage for the VCO tuning. In the locked mode, the VCO
is controlled by the phase detector and in unlocked mode,
the frequency detector is superimposed. The VCO
operates with an external resonance circuit (L and C par-
allel) and is controlled by internal varicaps. The VCO
control voltage is also converted to a current and repre-
sents the AFC output signal at Pin 22.

A practicable VCO alignment of the external coil is the
adjustment to zero AFC output current at Pin 22. At center
frequency the AFC output current is equal to zero.

The optional potentiometer at Pin 26 allows an offset
compensation of the VCO phase for improved sound
quality (fine adjustment). Without a potentiometer (open
circuit at Pin 26), this offset compensation is not active.

The oscillator signal passes a phase shifter and supplies
the in-phase signal (0

) and the quadrature signal (90

)of

the generated picture carrier.

Video Demodulation and Amplifier

The video IF signal, which is applied from the gain
controlled IF amplifier, is multiplied with the inphase
component of the VCO signal. The video demodulator is

designed for low distortion and large bandwidth. The
demodulator output signal passes an integrated low pass
filter for attenuation of the residual vision carrier and is
fed to the video amplifier. The video amplifier is realized
by an operational amplifier with internal feedback and
8 MHz bandwidth (3 dB). An additional noise clipping
is provided. The video signal is fed to VIF-AGC and to the
video output buffer. This amplifier with a 6 dB gain offers
easy adaption of the sound trap. For nominal video IF
modulation the video output signal at Pin 12 is 2 V

pp.

Sound IF Amplifier and SIF-AGC

The SIF amplifier is nearly identical with the 3-stage VIF
amplifier. Only the first amplifier stage exists twice and
is switchable by a control voltage at Pin 3. Therefore with
a minimal external expense it is possible to switch
between two different SAW filters. Both SIF inputs
features excellent cross-talk attenuation and an input
impedance which is independent from the switching
condition.

The SIF-AGC is related to the average level of FM-carrier
and controls the SIF amplifier to provide a constant SIF
signal to the QPS mixer.

Quasi-Parallel-Sound (QPS) Mixer

The QPS mixer is realized by a multiplier. The SIF signal
(FM or NICAM carrier) is converted to the intercarrier
frequency by the regenerated picture carrier (quadrature
signal) which is provided from the VCO. The intercarrier
signal is fed via an output amplifier to Pin 24.

AFC Switch

The AFC output signal at Pin 22 can be controlled by a
switching voltage at Pin 19. It is possible to switch off the
AFC.

VCR Mode

For the VCR mode in a TV set (external video source
selected), it is recommendable to switch off the IF circuit.
With an external switching voltage at Pin 6 or 7, the IF
amplifiers are switched off and all signal output levels at
Pins 12 and 24 are according to the internal dc voltage.

Internal Voltage Stabilizer

The internal bandgap reference ensures constant perfor-
mance independent of supply voltage and temperature.

TDA4472-M

TELEFUNKEN Semiconductors

Rev. A2, 15-Oct-96

Preliminary Information

4 (14)

Pin Description

i,SIF1

GND

AGC

i,SIF1

i,VIF

AGC

GND

top

tun

o,vid

i,SIF2

comp

o,FM

AFC

VCO

Vsw

ref

GND

94 8835

Figure 2. Pinning

Symbol

Function

1, 2

SIF1

SIF1 input (symmetrical)

Input selector switch

4, 9, 16

GND

Ground

AGC

SIF-AGC (time constant)

6, 7

i, VIF

VIF input (symmetrical)

AGC

VIF-AGC (time constant)

top

Take over point, tuner AGC

tun

Tuner AGC output current

o,vid

Video output

Not connected

ref

Internal reference voltage

Loop filter

AFC switch

20, 21

VCO

VCO circuit

AFC

AFC output

Supply voltage

Intercarrier output

Not connected

comp

Offset compensation

27, 28

i, SIF2

SIF 2 input (symmetrical)

TDA4472-M

Preliminary Information

TELEFUNKEN Semiconductors
Rev. A2, 15-Oct-96

5 (14)

Absolute Maximum Ratings

Reference point Pin 4 (9, 16), unless otherwise specified

Parameters

Symbol

Value

Unit

Supply voltage

Pin 23

SDIP28 package
SO28 package

9.0
6.0

V
V

Supply current

Pin 23

Power dissipation

SDIP28 package
SO28 package

P
P

840
560

mW
mW

Output currents

Pins 12 and 24

out

External voltages

Pins 1, 2, 5 to 8, 10, 12, 17, 18 and 24, 26 to 28
Pins 20 and 21
Pin 11
Pins 3, 19 and 22

ext

+4.5
+3.5

+13.5

V
V
V
V

Junction temperature

+125

Storage temperature

stg

25 to +125

Electrostatic handling

all pins

ESD

"300

Equivalent to discharging a 200 pF capacitor trough a 0

W resistor.

Operating Range

Parameters

Symbol

Value

Unit

Supply voltage range

Pin 23

SDIP28 package
SO28 package

4.5 to 9.0
4.5 to 6.0

V
V

Ambient temperature

amb

10 to +85

Thermal Resistance

Parameters

Symbol

Maximum

Unit

Junction ambient, when soldered to PCB

SDIP28 package
SO28 package

thJA

55
75

K/W
K/W

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