Datasheet

Efficiency of a BTL amplifier +
P
L
P
SUP
Where:
P
L
+
V
L
rms
2
R
L
, andV
LRMS
+
V
P
2
Ǹ
, therefore, P
L
+
V
P
2
2R
L
P
L
= Power delivered to load
P
SUP
= Power drawn from power supply
V
LRMS
= RMS voltage on BTL load
R
L
= Load resistance
V
P
= Peak voltage on BTL load
I
DD
avg = Average current drawn from the power supply
V
DD
= Power supply voltage
η
BTL
= Efficiency of a BTL amplifier
and
P
SUP
+ V
DD
I
DD
avg
and
I
DD
avg +
1
p
ŕ
p
0
V
P
R
L
sin(t) dt
+ *
1
p
V
P
R
L
[cos(t)]
p
0
+
2V
P
p R
L
Therefore,
P
SUP
+
2 V
DD
V
P
p R
L
substituting P
L
and P
SUP
into equation 6,
Efficiency of a BTL amplifier +
V
P
2
2 R
L
2 V
DD
V
P
p R
L
+
p V
P
4 V
DD
V
P
+ 2 P
L
R
L
Ǹ
Where:
h
BTL
+
p 2 P
L
R
L
Ǹ
4 V
DD
Therefore,
TPA6211A1
www.ti.com SLOS367D –AUGUST 2003– REVISED JUNE 2011
(14)
(15)
Table 2. Efficiency and Maximum Ambient Temperature vs Output Power
Output Power Efficiency Internal Dissipation Power From Supply Max Ambient Temperature
(1)
(W) (%) (W) (W) (°C)
5-V, 3-Ω Systems
0.5 27.2 1.34 1.84 85
(2)
1 38.4 1.60 2.60 76
2.45 60.2 1.62 4.07 75
3.1 67.7 1.48 4.58 82
5-V, 4-Ω BTL Systems
0.5 31.4 1.09 1.59 85
(2)
1 44.4 1.25 2.25 85
(2)
2 62.8 1.18 3.18 85
(2)
2.8 74.3 0.97 3.77 85
(2)
5-V, 8-Ω Systems
0.5 44.4 0.625 1.13 85
(2)
1 62.8 0.592 1.60 85
(2)
1.36 73.3 0.496 1.86 85
(2)
1.7 81.9 0.375 2.08 85
(2)
(1) DRB package
(2) Package limited to 85°C ambient
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