TDA2579C View Datasheet(PDF) - Philips Electronics

Part Name

Description

Manufacturer

TDA2579C

Synchronization circuit with synchronized vertical divider system for 60 Hz

Philips Electronics 

Philips Semiconductors

Synchronization circuit with synchronized

vertical divider system for 60 Hz

Preliminary specification

TDA2579C

PINNING

SYMBOL

VOUT

FB

SAW

VDC

VID

CSL

RSL

ϕ1

GND

VP

HOUT

FLYB

MUTE

HSHIFT

HOSC

STAB

SC

DET

PIN

DESCRIPTION

1 vertical driver output

2 vertical feedback input

3 vertical sawtooth generator

4 vertical deflection current output

5 video signal input

6 slicing level storage capacitor

7 slicing level resistor

8 phase detector ϕ1

9 ground (0 V)

10 main supply voltage (+12 V)

11 horizontal driver output

12 horizontal flyback pulse input

13 mute output

14 horizontal picture shift capacitor

15 horizontal oscillator frequency

setting

16 start circuit stabilizer input

17 sandcastle output

18 coincidence detector output

VOUT 1

18 DET

FB 2

17 SC

SAW 3

16 STAB

VDC 4

VID 5

CSL 6

TDA2579C

15 H OSC

14 H SHIFT

13 MUTE

RSL 7

ϕ1 8

GND 9

12 FLYB

11 H OUT

10 VP

MGA790

Fig.2 Pin configuration.

FUNCTIONAL DESCRIPTION

The TDA2579C generates both horizontal and vertical

drive signals, a 3-level sandcastle output pulse, a

transmitter identification signal and 60 Hz window

information.

The horizontal oscillator and horizontal output stage

functions are started via the supply current into pin 16.

The required current has a typical value of 5 mA which can

be taken directly from the mains rectifier. The horizontal

output transistor at pin 11 is not conducting until the supply

current at pin 16 has reached its typical value. The starting

circuit has a hysteresis of approximately 1 mA. The

horizontal output current of pin 11 starts at a duty cycle of

60%. All other IC functions are enabled via the main supply

voltage on pin 10.

The pin 16 supply system enables slaved synchronized

switch mode systems in which the horizontal output signal

of the TDA2579C is used as master signal. In such a

system the 12 V supply (main supply at pin 10) can be

generated by the line output stage.

An internal Zener diode reference voltage is used for the

vertical processing part. The IC embodies a synchronized

divider system for generating the vertical sawtooth at

pin 3. Thus no vertical frequency adjustment is required.

The circuit operation is restricted to the M (fV = 60 Hz)

system.

Vertical part (pins 1, 2, 3 and 4)

The IC embodies a synchronized divider system for

generating the vertical sawtooth at pin 3. The divider

system has an internal frequency doubling circuit, thus the

horizontal oscillator is operating at its nominal line

frequency and one line period equals 2 clock pulses.

No vertical frequency adjustment is required due to the

divider system. The divider system operates with

3 different reset windows for maximum

interference/disturbance protection.

The windows are activated via an up/down counter.

The counter increases its value by 1 each time the

separated vertical sync pulse is within the window being

searched. The count is reduced by 1 when the vertical

sync pulse is not present.

The reset of the counter system (clock pulse 0) is at half a

line period after the start of the vertical pulse at pin 5.

January 1994

5

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