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

mute

(pin 13)

gating

ϕ1 detector

ϕ1 detector

I8 0.35 mA

ϕ2 detector

I8 1.0 mA

not gated

ϕ3 detector

I8 0.65 mA

not gated

voltage

(pin 18)

1

0

1

0

1

0

1

0

1

A

0.1 V

0

B

C

D

E

F

G

1.2 V 1.8 V

3.5 V

5V

7.8 V

MGA792

Fig.3 Operation of the three phase detector circuits.

Explanation of areas A to G shown in Fig.3

A switching over to new TV station activates 3 field

period counter

B noise only condition

C TV transmitter identification hysteresis range

D fast time constant

C-E fast time constant hysteresis range

F normal time constant

G sync pulse noise level detection circuit forces

pin 18 to >7.8 V while signal-to-noise level

<19 dB; slow time constant and gated sync pulse

operation.

Supply (pins 9, 10 and 16)

The IC has been designed such that the horizontal

oscillator and output stage operate a very low supply

current into pin 16. The horizontal oscillator starts at a

supply current of approximately 4 mA (V16 approximately

6 V). The horizontal output stage is forced into the

non-conducting stage until the supply current has reached

a typical value of 5 mA.

The circuit has been designed such that after starting the

horizontal output function, a current drop of approximately

1 mA is allowed.

The starting circuit has the ability to derive the main supply

(pin 10) from the horizontal output stage. The horizontal

output signal can also be used as oscillator signal for

synchronized switched-mode power supplies.

January 1994

9

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