PAM8006
10W Stereo Class-D Audio Power Amplifier
Test Setup for Performance Testing
PAM8006 Demo Board
Load
Audio Precision
(AP) System
Generator
+OUT
Input
-OUT
VDD
AP
Low Pass
Filter
GND
AUX-0025
AP System
Analyzer
Power Supply
Notes
1. The Audio Precision(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 effic iency
measurement.
Application Information
Power and Heat Dissipation
Choose speakers that are able to stand large
output power from the PAM8006. Otherwise,
speaker may suffer damage.
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.
In operation, some of power is dissipated to the
resistors.
Power Dissipation: P
loss
=(Po*(1-
η)/ η)*
2
The PAM8006’ efficiency is 90% with 10W ouput
s
and 8
Ω
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
loss
*
θ
jA+Ta, where Ta is ambient
temperature. If the ambient temperature is 85°
C,
the QFN’ junction temperature
s
Tj=2.22*18.1+85=125°
C
w hi c h is l o we r th a n 1 5 0° r a t ed j un c ti o n
C
temperature.
If the rated workable junction temperature is
150° , the relationship between ambient
C
temperature and permitted P
loss
is shown in below
diagram.
10
9
8
7
6
5
4
3
2
1
0
0
20
40
Ta
60
80
100
From the diagram, it can be found that when the
device works at 10W/8
Ω
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 PAM8006 can
work in full output power under 85° ambient
C
temperature.
Power Analog Microelectronics
,
Inc
www.poweranalog.com
9
03/2011 Rev1.0
PAM [ POWER ANALOG MICOELECTRONICS ]
