Datasheet

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THERMAL CONSIDERATIONS
R
L
= 8 Ω
R
L
= 16 Ω
V
DD
= 5 V
Two Channels Active
80
60
40
20
0 0.25
- Free-Air Temperature -
120
140
160
0.5 0.75
100
P
O
max - Maximum Output Power - W
C
°T
A
5-V VERSUS 3.3-V OPERATION
TPA302
SLOS174C – JANUARY 1997 – REVISED JUNE 2004
A prime consideration when designing an audio amplifier circuit is internal power dissipation in the device. The
curve in Figure 43 provides an easy way to determine what output power can be expected out of the TPA302 for
a given system ambient temperature in designs using 5-V supplies. This curve assumes no forced airflow or
additional heat sinking.
Figure 43. Free-Air Temperature Versus Maximum Output Power
The TPA302 was designed for operation over a supply range of 2.7 V to 5.5 V. This data sheet provides full
specifications for 5-V and 3.3-V operation because they are considered to be the two most common standard
voltages. There are no special considerations for 3.3-V versus 5-V operation as far as supply bypassing, gain
setting, or stability. Supply current is slightly reduced from 4 mA (typical) to 2.25 mA (typical). The most important
consideration is that of output power. Each amplifier in the TPA302 can produce a maximum voltage swing of
V
DD
– 1 V. This means, for 3.3-V operation, clipping starts to occur when V
O(PP)
= 2.3 V as opposed when
V
O(PP)
= 4 V while operating at 5 V. The reduced voltage swing subsequently reduces maximum output power
into the load before distortion begins to become significant.
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