12

,

Power Analog Microelectronics Inc

08/2008 Rev 1.2

PAM8610

10W Stereo Class-D Audio Power Amplifier with DC Volume Control

www.poweranalog.com

Application Information

Power and Heat Dissipation

Choose speakers that are able to stand large

output power from the PAM8610. Otherwise,

speaker may suffer damage.

In operation, some of power is dissipated to the

resistors.

The PAM8610’s efficiency is 90% with 10W ouput

and 8

load. The dissipation power is 2.22W.

Thermal resistance of junction to ambient of the

QFN package is 18.1°C/W and the junction

temperature Tj=P

* jA+Ta, where Ta is ambient

temperature. If the ambient temperature is 85°C,

the QFN’s junction temperature

Tj=2.22*18.1+85=125°C

which i s lower than 150°C r ated junction

temperature.

If the rated workable junction temperature is

150°C, the r elationship between ambient

temperature and permitted P

is shown in below

diagram.

From the diagram, it can be found that when the

device works at 10W/8

load the dissipation

power is 1.1W per channel, 2.2W total, the

permitted ambient temperature is over 100°C.

This is proven by actual test. The PAM8610 can

work in full output power under 85°C ambient

temperature.

Ω

θΩ

loss

loss

Heat dissipation is very important when the

device works in full power operation. Two factors

affect the heat dissipation, the efficiency of the

device that determines the dissipation power, and

the thermal resistance of the package that

determines the heat dissipation capability.

Power Dissipation: P

=(Po*(1-

2

loss

η)/η)*

0

1

2

3

4

5

6

7

8

9

10

0

2040

6080

100

Ta

Notes

1. The AP AUX-0025 low pass filter is necessary for class-D amplifier measurement with AP analyzer.

2. Two 22μH inductors are used in series with load resistor to emulate the small speaker for efficiency

measurement.

Test Setup for Performance Testing

AP System One

Generator

PAM8610 Demo Board

+OUT

Input

Load

AP

Low Pass

Filter

AUX-0025

AP System One

Analyzer

GND

-OUT

VDD

Power Supply