No. 5636-10/16

LA7565B, 7565BM

Pin No.

Pin

Pin function

Equivalent circuit

5

6

7

8

EQ amp

separation as possible.

Connections for the equalizer circuit. This circuit corrects the

frequency characteristics of the video signal.

Pin 17 is the equalizer amplifier input. A 1.5-Vp-p video

signal is input and amplified to 2.0 Vp-p by the equalizer

amplifier.

The equalizer amplifier is designed as a voltage-follower

amplifier with a gain of about 2.3 dB. When frequency

characteristic correction is used, a capacitor, an inductor,

and a resistor must be connected in series between pin 7

and ground.

• Using the equalizer amplifier

If vi is the input signal and vo is the output signal, then:

R1/Z + 1 (vi + vin) = Vo

× G

Where,

G: Gain of the voltage follower amplifier

vin: Imaginary short

G: About 2.3 dB

Assuming vin

≈ 0:

Then,

AV = voG/vi = R1/Z + 1.

R1 is an IC internal resistor with a value of 1 k

Ω. Simply

select a Z according to the desired characteristics. However,

since the equalizer amplifier is maximum at the Z resonance

point, care is required to prevent distortion from occurring at

that frequency.

Continued from preceding page.

9

APC filter

PLL detector APC filter connection.

The APC time constant is switched internally. When the PLL

is locked, the VCO is controlled over the path marked A in

the figure and the loop gain is lowered. When the PLL is

unlocked and in weak field reception conditions, the VCO is

controlled over the path marked B in the figure and the loop

gain is increased.

We recommend values of:

R = between 150 and 390

Ω, and

C = 0.47 µF

for this APC filter.

Continued on next page.