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

• IF AGC filter connection.

The AGC voltage is created at pin 7 from the signal to which

peak detection was applied by the internal AGC detector.

7

IF AGC

Additionally, the IC includes an internal second AGC filter (a

lag-lead filter) used to create a dual time constant. A 0.022 µF

capacitor is used as the external capacitor. The value of this

capacitor must be adjusted according to measurement of the

sag, AGC speed, and other circuit aspects.

Equivalent circuit

• First SIF input.

A DC cut capacitor must be inserted in the input to this circuit.

When a SAW filter is used: The first SIF sensitivity can be

8

1st SIF IN

increased by inserting an inductor between the SAW and the IC

to match the SAW output and IC input capacitances.

When an intercarrier system is used: This pin must be

connected to ground through a capacitor.

• RF AGC output.

This output controls the tuner RF AGC. This is an open-

9

RF AGC OUT

collector output with an inserted 100-Ω protective resistor.

Determine the value of the external bleeder resistor to match

the tuner specifications.

• AFT output.

The AFT center voltage is created with an external bleeder

resistor. The AFT gain increases as the value of this bleeder

10

AFT OUT

resistor increases. The value of this resistor must not exceed

390 kΩ. This circuit includes a control function that controls the

AFT voltage to be equal to the center voltage in weak field

reception conditions.

Continued on next page.

No. 5764-7/11

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