Proper Cares in Operating a Set with LA4183 Incorporated

When a set with the LA4183 incorporated is operated from AC power supply, a momentary drop in supply voltage is caused by

the transformer regulation, etc. at the time of turning ON the motor with the circuit shown below. In this case, if ripple noise is

generated from the speaker or headphone, take the following actions.

1.

the voltage at pin 6 can follow the supply voltage regulation. In the steady state, this diode is cut off.

2.

Increase the capacity of the power source capacitor so that the supply voltage regulation can be minimized.

Radiation Design

.

Since the DIP 12-pin package is so designed as to be able to radiate heat through the Cu-foiled area of printed circuit board

under normal operating conditions, make the Cu-foiled area near the fin of IC as large as possible when designing the printed

circuit board.

.

By providing the Cu-foiled area covered by the broken line as shown in the above-mentioned example of printed circuit pattern,

a rather satisfactory radiation is enabled. (Refer to the Pd − Ta characteristics.)

.

Since the power dissipation (Pd) goes higher depending on the conditions of supply voltage and load, it is recommended to use

the fin together with the printed circuit board.

.

The following equations are rule-of-thumb guides for Pd (for stereo). For AC power supply, it is desirable to measure with the

transformer of each individual set. In the bridge amplifier application, calculation should be made with 1/2 of the load used.

(1) DC Power supply

Pd max =

2

L

(2) AC power supply

.

Example of fin mounting

The fin is formed into such a shape as to be able to radiate heat from the plastic area of IC and the fin as shown below and is

soldered to the printed circuit board. For the fin size, refer to the Pd – Ta characteristics. The desirable material is copper or

iron which is solderable. It is recommended to apply silicone grease, etc. to the plastic area of IC in order to minimize the

thermal resistance.

Pd max =

2

L

Quiescent supply voltage

Quiescent current

1+

√2 v π v R

L

×

Supply voltage at max. output

r: Voltage regulation,

LA4183

No.887-6/11