AS1710/AS1712
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
8 Application Information
Package Power Dissipation
Caution:
Due to the high output current drive, this op amp can exceed the absolute maximum power-dissipation rat-
ing. Normally, when peak current is less than or equal to 40mA the maximum package power dissipation is
not exceeded for any of the package types offered.
The absolute maximum power-dissipation rating of each package should always be verified. (EQ 1) gives an approxi-
mation of the package power dissipation:
P
PACKAGEDISS
≅
V
RMS
I
RMS
COS
θ
Where:
V
RMS
is the RMS voltage from V
DD
to V
OUT
when sourcing current, and from V
OUT
to V
SS
when sinking current.
I
RMS
is the RMS current flowing in or out of the op amp and the load.
θ
is the phase difference between the voltage and the current. For resistive loads, COS
θ
= 1.
Figure 21. Typical AS1710/AS1712 Single-Supply Application
3.6V
(EQ 1)
R
C
V
IN
= 2V
P-P
R
+
AS1710
–
32Ω
V
RMS
can be calculated as:
V
RMS
≅
(V
DD
- V
DC
) + V
PEAK
/
√
2
Where:
V
DC
is the DC component of the output voltage.
V
PEAK
is the highest positive excursion of the AC component of the output voltage.
For the circuit shown in
V
RMS
= (3.6V - 1.8V) + 1.0V/
√
2 = 2.507V
RMS
I
RMS
can be calculated as:
I
RMS
≅
IDC + (IPEAK/
√
2)
Where:
I
DC
is the DC component of the output current.
I
PEAK
is the highest positive excursion of the AC component of the output current.
For the circuit shown in
I
RMS
= (1.8V/32Ω) + (1.0V/32Ω)/
√
2 = 78.4mA
RMS
Therefore, for the circuit in
the package power dissipation can be calculated as:
P
PACKAGEDISS
= V
RMS
I
RMS
COS
θ
= 196mW
Adding a coupling capacitor improves the package power dissipation because there is no DC current to the load, as
shown in
(EQ 3)
(EQ 2)
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