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Pin

No.

Symbol

Circuit Configuration

Description

24

SIF INPUT, J/U SW

Pin 24 is used both for SIF input and J/U

SW audio mute.

.

The input impedance is approximately

1.5 k

Ω.

.

J/U (Japan/U.S.) switch

The oscillating frequency for VCO2 in

Japan and the U.S. differs. However, the

center frequency of the SIF detector is

controlled using VCO2 as a reference. As

a result, the filter control mode can be

changed either by leaving this pin open or

dropping it to GND through a 3.9 k

Ω

resistor.

Open: Japan mode

3.9 k

Ω: U.S. mode

.

Audio mute:

Audio muting can be applied by dropping

the voltage on this pin to 0.5 V or less.

LA7583 VCO COIL design considerations

1. Design criteria

Allow for an adequate variable range for the IF frequency in the design. Specifically, select a coil value so that the carrier

frequency is roughly in the center of the characteristics diagram shown below when 2 V and 4 V are applied to pin 22.

2. Design notes

a. When selecting the L value, the LA7583 must be soldered directly on the board. If an IC socket is used, an error in the VCO

center frequency will arise from the capacitance of the socket.

b. The patterns for pins 13 and 14 must be made as short as possible (15 mm or less). Minimize the effect of the printed

pattern.

c. A VCO coil of which tolerance is ± 5% must be used.

3. Measuring the IF frequency range

Drop the IF AGC (pin 4) to GND. Next, pick up the VCO carrier leak at a pin other than the VCO coil (pins 13 and 14) and

read the carrier frequency. And then, apply a voltage ranging from 1.5 V to 4.5 V to pin 22, and record the characteristics of the

maximum variable frequency range for VCO as shown in the diagram below.

4. Recommended VCO coil

A. Tokyo Parts Industry Co., Ltd.

5LC

JAPAN

1.2 µH ± 5%

U.S.

1.8 µH ± 5%

Y22−V

Y22−V

LA7583

No.5177-13/15