TELEFUNKEN Semiconductors

TDA4474

Preliminary Information

Rev. A1: 17.08.1995

5 (17)

SIF amplifier output is multiplied in phase with the

limited SIF signal (AM is removed). The AF signal of the

demodulator output is fed to the output amplifier and to

the SIF–AGC. For all TV standards with negative video

modulation (e.g. B/G standard) the AF output signal

(Pin 27) is switched off by the standard switch.

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 26.

Standard Switch

To have equal polarity of the video output signal the

polarity can be switched in the demodulation stage in

accordance with the TV standard. Additional a standard

dependent DC level shift in the video amplifier delievers

the same sync level. Parallel the correct VIF–AGC is

selected for positive or negative modulated VIF signals.

In case of negative modulation (e.g. B/G standard) the

AM output signal is switched off. If the standard for

positive modulation (L standard) is selected the AM

demodulator and QPS mixer is active. This condition

allows a parallel operation of the AM sound signal and the

NICAM–L stereo sound.

L’ Switch and VIF Input Selection

For positive modulated signals (L/L’ standard) Pin 16

works as L’ switch. With a control voltage the VCO

frequency can be switched for setting to the required

L’ value (L’ standard). Also a fine adjustment of the

L’-VCO centre frequency is possible by a potentiometer.

The L’ switch is only active for positive modulated video

IF signals (standard switch in L mode). In this mode the

video IF input 2 (VIF2) is forced by the standard switch.

The possibility to select VIF1 input is given by

connecting VIF2 input (Pin 10 or 11) via 10 k resistor to

ground.

If negative modulation (B/G mode) is selected pin 16 op-

erates as an input selection switch for the two VIF inputs.

AFC Switch

The AFC output signal at Pin 24 can be controlled by a

switching voltage at Pin 21. It is possible to select an AFC

output signal with rising– or falling AFC curve and to

switch off the AFC.

Internal Voltage Stabilizer

The

internal

bandgap

reference

ensures

constant

performance

independant

of

supply

voltage

and

temperature.

Absolute maximum values

Reference point pin 4 (9, 18), unless otherwise specified

Parameters

Symbol

Value

Unit

Supply voltage

Pin 25

9 0

V

Supply current

Pin 25

85

mA

P

765

mW

Output currents

Pin 14 26, 27

5

mA

External voltages

Pins 1, 2, 5–8, 10–12,

14, 16, 19, 20, 26–30

+ 4.5

V

Pins 17, 22, 23

+ 3.5

V

Pin 13

+ 13 5

V

Pins 3, 15, 21, 24

V

Junction temperature

+125

°C

Storage temperature

25 to +125

°C

Electrostatic handling *)

all pins

300

V

*) Equivalent to discharging a 200 pF capacitor through a 0 resistor

Operating Range

Parameters

Symbol

Value

Unit

Supply voltage range

Pin 25

4 5 to 9 0

V

Ambient temperature

0 to +85

°C