TS489 STMicroelectronics, TS489 Datasheet - Page 22

• Manufacturer Part Number: TS489
• Description: Pop-free 120mW stereo headphone amplifier
• Manufacturer: STMicroelectronics

Application information
4
4.1
22/32
Application information
Power dissipation and efficiency
Hypotheses:
■
■
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:
Voltage and current in the load are sinusoidal (V
Supply voltage is a pure DC source (V
Vpeak/R
Icc
Icc (t)
AVG
L
0
I
CC
AVG
P
diss
=
T/2
------
2π
P
1
P
V
diss
=
supply
OUT
∫
0
π
P
------------------ - P
I
OUT
V
---------------- -
π R
OUT
=
2V
PEAK
R
∂P
∂
=
P
P
CC
L
=
CC
L
supply
V
diss
OUT
=
=
T
V
).
PEAK
sin
V
---------------- - A
V
-------------- A
CC
2R
R
2
PEAK
OUT
OUT
t ( )
=
I
–
L
CC
sin
L
P
0
t d
( )
OUT
AVG
–
( )
out
ωt V
=
P
3T/2
( )
(
(
OUT
W
and I
V
---------------- - A
W
πR
PEAK
)
)
(
L
W
out
)
( )
).
2T
Time
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