LA7566 View Datasheet(PDF) - SANYO -> Panasonic

Part Name

Description

Manufacturer

LA7566

VIF/SIF IF Signal-Processing Circuit with TV/VCR PAL and NTSC Multisound Support

SANYO -> Panasonic 

Continued from preceding page.

Pin No.

Symbol

LA7566

Pin function

11

• VCO tank circuit used for video detection.

12

VCO

See the separately provided documentation for the tank circuit

coil (inductor) specifications.

Equivalent circuit

• Equalizer circuit. This circuit corrects the video signal frequency

characteristics.

• Notes on equalizer amplifier design:

The equalizer amplifier is designed as a voltage follower

amplifier with a gain of about 2.3 dB. When the frequency

characteristics are corrected, connect an inductor, a capacitor,

13

VIDEO OUT

and a resistor in series between pin 14 and ground.

14

EQ FILTER

The equalizer amplifier gain is given by:

R1

AV = —— + 1

Z

Here, R1 is an IC internal resistor with a value of 1 kΩ. Select Z

according to the desired characteristics. However, care is

required to prevent distortion at the resonant point determined

by Z, where the gain is maximum.

15

PAL VIDEO IN

• Equalizer amplifier inputs.

16

NT VIDEO IN

Pin 15 is for PAL, and pin 16 for NTSC format signals. These

inputs are linked to and switched by the SIF switches.

• PLL detector APC filter connection.

The APC time constants are switched internally in the IC. When

locked, the VCO is controlled over the path A, and the loop gain

is reduced. When unlocked and during weak field reception, the

VCO is controlled over the path B, thus increasing the loop

17

APC FILTER

gain.

We recommend values of:

R = 150 to 390 Ω, and

C = 0.47 µF

for the loop filter constants.

Continued on next page.

No. 5764-8/11

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