Datasheet

TS488-TS489 Application information
Doc ID 11971 Rev 5 23/32
and its value is:
Note: This maximum value depends only on power supply voltage and load values.
The efficiency is the ratio between the output power and the power supply:
The maximum theoretical value is reached when V
peak
= V
CC
/2, so
4.2 Total power dissipation
The TS488/9 is stereo (dual channel) amplifier. It has two independent power amplifiers.
Each amplifier produces heat due to its power dissipation. Therefore the maximum die
temperature is the sum of each amplifier’s maximum power dissipation. It is calculated as
follows:
P
diss R
= Power dissipation due to the right channel power amplifier.
P
diss L
= Power dissipation due to the left channel power amplifier.
Total P
diss
=P
diss R
+P
diss L
(W)
Typically, P
diss R
is equal to P
diss L
, giving:
4.3 Lower cutoff frequency
The lower cutoff frequency F
CL
of the amplifier depends on input capacitors C
in
and output
capacitors C
out
.
The input capacitor C
in
(output capacitor C
out
) in serial with the input resistor R
in
(load
resistor R
L
) of the amplifier is equivalent to a first order high pass filter. Assuming that F
CL
is
the lowest frequency to be amplified (with a 3 dB attenuation), the minimum value of the C
in
(C
out
) is:
P
diss
MAX
V
CC
2
π
2
R
L
-------------
W()=
η
P
OUT
P
supply
-------------------
πV
peak
2V
CC
------------------ -==
η
π
4
--- 78.5%==
TotalP
diss
2P
dissR
2P
dissL
==
TotalP
diss
22V
CC
π R
L
----------------------
P
OUT
2P
OUT
=
C
in
1
2π F
CL
R
in
⋅⋅
----------------------------------=
C
out
1
2π F
CL
R
L
⋅⋅
---------------------------------=