Diodes PAM8610 - Manual (Page 9)

PAM8610
Document number: DSxxxxx Rev. 1 - 2
9 of 15
www.diodes.com
June 2013
© Diodes Incorporated
PAM8610
A Product Line of
Diodes Incorporated
Application Information
Test Setup for Performance Testing
Notes:
4. The AP AUX-0025 low pass filter is necessary for class-D amplifier measurement with AP analyzer.
5. Two 22 μH inductors are used in series with load resistor to emulate the small speaker for efficiency measurement.
Power and Heat Dissipation
Choose speakers that are able to stand large output power from the PAM8610. 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
= (P
O
*(1- η/η)*2
The PAM8610’s efficiency is 90% with 10W ouput 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 T
J
= P
LOSS
* θ
JA
+T
A
, where T
A
is
ambient temperature. If the ambient temperature is +85°C, the QFN’s junction temperature
T
J
= 2.22*18.1 + 85 = +125°C
which is lower than +150°C rated junction temperature.
If the rated workable junction temperature is 150°C, the relat ionship between ambient temperature and permitted P
LOSS
is shown in below
diagram.
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 PAM8610 can work in full output power under +85°C ambient
temperature.