STK433-290-E

No. A1630-9/13

[Example]

When the IC supply voltage, VCC, is ±33V and RL is 6Ω, the total power dissipation, Pd, within the hybrid IC, will

be a maximum of 109.7W at 1kHz for a continuous sine wave signal according to the Pd-PO characteristics.

For the music signals normally handled by audio amplifiers, a value of 1/8PO max is generally used for Pd as an

estimate of the power dissipation based on the type of continuous signal. (Note that the factor used may differ

depending on the safety standard used.)

This is:

Pd

≈ 85.0W

(when 1/8PO max. = 10W, PO max. = 80W).

The number of power transistors in audio amplifier block of these hybrid ICs, N, is 6, and the thermal resistance per

transistor,

θj-c, is 2.1°C/W. Therefore, the required heat sink thermal resistance for a guaranteed ambient temperature,

Ta, of 50

°C will be as follows.

From formula (1)'

θc-a < (125 − 50)/85.0

< 0.88

From formula (2)'

θc-a < (150 − 50)/85.0 − 2.1/6

< 0.82

Therefore, the value of 0.82

°C/W, which satisfies both of these formulae, is the required thermal resistance of the heat

sink.

Note that this thermal design example assumes the use of a constant-voltage power supply, and is therefore not a

verified design for any particular user’s end product.

STK433-300series Stand-by Control & Mute Control & Load-Short Protection

Application

(*1) The impression voltage of a Stand-by terminal (#13) is

the maximum rating (VST max). Please set up not to exceed.

+5V

+5V

Stand-by Control

Mute Control

ST-BY

PLAY

ST-BY

MUTE

MUTE

STK433-300 series

56k

Ω

2

3

4

5

8

7

6

9

10

11

12

13

14

15

1

GND

+VCC

-VCC

56k

Ω

6.8k

Ω

6.8k

Ω

Ch2 IN

GND

Ch1 IN

10k

Ω

10k

Ω

10k

Ω

2.2k

Ω

Mute Control

H: Single Mute

L: Normal

Stand-by Control(ex)

H: Operation Mode(+5V)

L: Stand-by Mode(0V)

33

μF

/10V

33k

Ω

1k

Ω

2k

Ω

2.7k

Ω

SUB.GND

Ch2 OUT

Ch1 OUT

GND

GND

Load Short Protection

Circuit

10k

Ω

100k

Ω

56k

Ω

1k

Ω

22k

Ω

Latch Up

Circuit

16

17

18

19

GND

Ch3 OUT

Ch3 IN

10k

Ω

+VCC

Ch2

OUT

Ch1

OUT

-VCC

+PRE

Ch1

IN

Ch1

NF

Ch2

IN

Ch2

NF

ST-

BY

Ch3

NF

Ch3

IN

Ch3

OUT

SUB

GND

Ch2

OUT

Ch1

OUT

Ch3

OUT

-PRE

56k

Ω 6.8kΩ

0.1

μF