
TAS5110
SLES028A MAY 2002 REVISED SEPTEMBER 2002
15
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Thermal Methodology for the 32-Pin DAD Package 50 W, 6-
Test
The thermal test for the DAD part (e.g., thermal pad oriented away from the board) was conducted as shown
in Figure 7 and Figure 8. The cooling approach was to attach a heat sink to the thermal pad and conduct the
heat to ambient air.
Since the approach was to use a chassis below the board, it was inverted and a spacer bar used to connect
the pads thermally to the heat sink. The bar was made high enough that the components on the board were
clear of the chassis.
The pad-to-spacer thermal resistance was about 3.2
_C/W with the thermal compound indicated.
The chassis provided the only heat sink to air and was chosen as representative of a possible cooling approach.
A closed plastic top and insulating front and back panels ensured that only the bottom and sides of the U shaped
chassis contributed to cooling. The chassis was spaced 0.25 inch from the table to simulate a normal chassis
configuration. The thermal pad does not need to be isolated from ground. (Any heat sink with a thermal
resistance to air of 3.9
_C/W or lower also works.) In this test, the exposed chassis reached long-term equilibrium
temperatures above 50
_C, so the approach would have to be modified for touch temperature consideration. The
chassis temperature after 10 minutes of 50 W into 6
was below 50_C.
The test ran for three hours with 2 x 50 W RMS at 1 kHz into a 6-
resistive load at an ambient lab temperature
of 23
_C. No audio or thermal problems were encountered during that time.
32 DAD Package
Wakefield Type 126
Thermal Compound
(3.2
°C/W)
Aluminum Space Bar
(1/4 in Thick)
(2.44
°C/W)
Stereo Amplifier
Board
Wakefield Type 126
Thermal Compound
(0.169
°C/W)
1.25 in
Aluminum Chassis 7.2 in x 1 in x 0.1 in Thick
Sides of U-Shaped Chassis Are 1.25 in High
(3.9
°C/W)
Insulating
Back Panel
Insulating
Front Panel
Plastic Top Cover
Figure 7. 32-Pin DAD Package Cross-Sectional View (Side)