TPA1517
www.ti.com
SLOS162D–MARCH 1997–REVISED FEBRUARY 2007
The maximum ambient temperature depends on the heatsinking ability of the PCB system. The derating factor
for the NE package with 7 square inches (17.78 cm) of copper area is 22.8 mW/°C. Converting this to θJA:
1
θ
+
JA
Derating
1
+
For 0 CFM :
0.0228
+ 43.9°CńW
To calculate maximum ambient temperatures, first consider that the numbers from the dissipation graphs are per
channel so the dissipated heat needs to be doubled for two channel operation. Given θJA, the maximum
allowable junction temperature and the total internal dissipation, the maximum ambient temperature can be
calculated with the following equation. The maximum recommended junction temperature for the TPA1517 is
150°C.
T
Max + T Max * q
P
A
J
JA
D
(
)
(
)
+ 150 * 43.9 1.25 2 + 40°C 15 dB headroom, 0 CFM
Table 1 clearly shows that for most applications some airflow is required to keep junction temperatures in the
specified range. The TPA1517 is designed with thermal protection that turns the device off when the junction
temperature surpasses 150°C to prevent damage to the IC. Using the DWP package on a multilayer PCB with
internal ground planes can achieve better thermal performance. Table 1 was calculated for a maximum volume
system; when the output level is reduced, the numbers in the table change significantly. Also using 8-Ω
speakers dramatically increases the thermal performance by increasing amplifier efficiency.
NE THERMAL RESISTANCE, θJA
vs
COPPER AREA
90
80
70
60
50
40
30
20
10
0
0
1
2
3
4
5
6
7
8
9
10
Copper Area
Figure 26.
16
Submit Documentation Feedback
TI [ TEXAS INSTRUMENTS ]
