LA76818 Ver la hoja de datos (PDF) - Unspecified

Número de pieza

componentes Descripción

Fabricante

LA76818

The BUS Control Functions of LA76818 (Tentative)

Unspecified 

Technical Note of LA76818

2002/01/23

PIN 7 (IF GROUND)

This is the ground of IF circuit.

PIN 8 (IF Vcc)

This is DC voltage supply pin for IF circuit. Please add a 5.0Vdc to it.

PIN 9 (FM FILTER)

This is the filter pin for the DC loop of FM detector.

FM.Gain

Deem-TC

FM DET

+

-

WRITE

5BIT

FM LEVEL

2.5

V

FM AMP

De-emph

+

-

DC loop

２

９

＋

Using PLL FM detection will cause DC shift during detecting SIF from 4.5MHz

to 6.5MHz. But, this IC detects SIF signal from 4.5MHz to 6.5MHz at good linearity

range. Then it will pass through a amplifier after the DC output is fixed. In order to

keep the DC output constantly, feedback loop of the operating amplifier is built-in

into the IC. And it is also necessary to feedback a DC component, which is created by

the external capacitor of pin 9. The recommend value of this capacitor is 1uF. The

characteristic of low frequency and the respond time when FM signal input is

depending on the value of this capacitor. And it is also possible to decrease the FM

detection level by connecting a resister serially with pin 9.

1k

９

1k

1u

The circumference circuit of pin 9

20/ 46

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