LA7565BM データシートの表示（PDF） - SANYO -> Panasonic

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LA7565BM

IF Signal-Processing IC for PAL/NTSC Multi-System Audio TV and VCR Products

SANYO -> Panasonic 

LA7565B, 7565BM

Continued from preceding page.

Pin No.

Pin

5 VCC

Pin function

VCC and ground should be decoupled with as small a

separation as possible.

Equivalent circuit

6

7 EQ amp

8

Connections for the equalizer circuit. This circuit corrects the

frequency characteristics of the video signal.

Pin 8 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 kΩ. 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.

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.

No. 5636-10/17

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