375
m
m
(+0, -25
m
m)
275
m
m
(+0, -25
m
m)
Circular Solder Mask Opening
Paste Mask (Stencil)
= Copper Pad Size
75
m
m
100
m
m
100
m
m
100
m
m
100
m
m
100
m
m
75
m
m
75
m
m
EFFICIENCY AND THERMAL INFORMATION
q
JA
+
1
Derating Factor
(3)
T
A
Max
+
T
J
Max
*
q
JA
P
Dmax
(4)
TPA2035D1
SLOS562 – AUGUST 2008
................................................................................................................................................................................................
www.ti.com
Figure 33. Close Up of TPA2035D1 Land Pattern
The maximum ambient temperature depends on the heat-sinking ability of the PCB system. The derating factor
for the YZF package is shown in the dissipation rating table. Converting this to
θ
JA
:
Given
θ
JA
(from the Package Dissipation ratings table), the maximum allowable junction temperature (from the
Absolute Maximum ratings table), and the maximum internal dissipation (from Power Dissipation vs Output
Power figures) the maximum ambient temperature can be calculated with the following equation. Note that the
units on these figures are Watts RMS. Because of crest factor (ratio of peak power to RMS power) from 9–15
dB, thermal limitations are not usually encountered.
The TPA2035D1 is designed with thermal protection that turns the device off when the junction temperature
surpasses 150°C to prevent damage to the IC. Note that using speakers more resistive than 4-
Ω
dramatically
increases the thermal performance by reducing the output current and increasing the efficiency of the amplifier.
θ
JA
is a gross approximation of the complex thermal transfer mechanisms between the device and its ambient
environment. If the
θ
JA
calculation reveals a potential problem, a more accurate estimate should be made.
14
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