Datasheet

Application information TS488-TS489
22/32 Doc ID 11971 Rev 5
4 Application information
4.1 Power dissipation and efficiency
Hypotheses:
■ Voltage and current in the load are sinusoidal (V
out
and I
out
).
■ Supply voltage is a pure DC source (V
CC
).
Regarding the load we have:
and
and
The average current delivered by the power supply voltage is:
Figure 78. Current delivered by power supply voltage in single-ended configuration
The power delivered by power supply voltage is:
So, the power dissipation by each power amplifier is
and the maximum value is obtained when:
V
OUT
V
PEAK
ωtV()sin=
I
OUT
V
OUT
R
L
--------------
A()=
P
OUT
V
PEAK
2
2R
L
-----------------
A()=
I
CC
AVG
1
2π
------
V
PEAK
R
L
-----------------
t()sin td
0
π
∫
V
PEAK
πR
L
-----------------
A()==
Icc (t)
Time
T/2 T
Icc
AVG
Vpeak/R
L
03T/22T
P
supply
V
CC
I
CC
AVG
W()=
P
diss
P
supply
P
OUT
W()–=
P
diss
2V
CC
π R
L
-------------------
P
OUT
P
OUT
W()–=
P
OUT
∂
∂P
diss
0=