22nF

5k

Ω

6.2k

Ω

10k

Ω

100k

Ω

56k

Ω

22k

Ω

82k

Ω

47k

Ω

3.3k

Ω

P2

P1

3

4

11

5

AB

S1c

S1d

S1e

S2

13

12

2

10

614

1

TDA4433

150pF

5.6k

Ω

47nF

0or 3V (DC)

0or 3V (DC)

A

B

S1a

S1b

11k

Ω

11k

Ω

11k

Ω

0.1

µF

+V = 12V

S

Digital AFC

out TDA4433

Identif. out

Pos. Video in

Hor. Flyback in

H

L

L

H

H

L

out B

out A

(no ident.)

(ident.)

S1 A : Static tests

B : Functional tests

B : Functional tests

S2 A : DC or pulses width

P2 Sensitivity control

P1 Digital AFC perfect tuning

TEST CIRCUIT

APPLICATION INFORMATION

(refer to the block diagram)

TV Signal Identification Circuit

The circuit recognizes only TV signals by checking

logically during one line the coincidence between

the horizontal flyback pulse and the pulse detected

by a sync. separator.

The signal identification is carried out by charging

the capacitor connected to pin 5 ; when the capaci-

tor voltage overcomes a fixed threshold voltage, a

Schmitt trigger switches and enables the AFC con-

trol. If a TV signal is recognized, the capacitor is

slightly charged every line and its voltage reaches

the thresholdafter a number of line which is defined

by the value of the capacitor itself. The sensitivity

of the identification circuit, hence the number of

lines required to charge the capacitor, can be ad-

justed by means of the resistor connected between

pin 11 and ground.

When the identification has been made, a signal

(level L) is available at pin 10.

Threshold Circuit

The circuit detects 3 ranges of AFC voltage and in

combination with the TV signal identification circuit

drives the electronic switches.

With a correct TV signal, the output levels corre-

sponding to the 3 ranges are :

δf

High Level

Low Level

Low Level

Low Level

δf

Low Level

High Level

The TDA4433 has two separate outputs which can

have only two states, high (H) or low (L). The

outputs at pin 2 and at pin 6 remain at a low level

with no video signal input or with a video signal not

identified as a true TV signal. Both pin 2 and pin 6

are open collector outputs and must be pulled-up

to the positive supply voltage by external resistors.

Voltage Regulator

The circuit can deliver 1 mA and it can be used as

D/A converter reference to supply fine tuning volt-

age.

TDA4433

µP

M206

µP interface

With microprocessor

EPM SYSTEM CONFIGURATIONS

TDA4433

4/5