AS1712A 查看數據表（PDF） - austriamicrosystems AG
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AS1712A
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AS1712A Datasheet PDF : 17 Pages
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AS1710/AS1712
Data Sheet - Application Information
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:
PPACKAGEDISS ≅ VRMS IRMS COSθ
(EQ 1)
Where:
VRMS is the RMS voltage from VDD to VOUT when sourcing current, and from VOUT to VSS when sinking current.
IRMS 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, COSθ = 1.
Figure 21. Typical AS1710/AS1712 Single-Supply Application
3.6V
R
C
VIN = 2VP-P
+
R
AS1710
–
32Ω
VRMS can be calculated as:
VRMS ≅ (VDD - VDC) + VPEAK /√2
(EQ 2)
Where:
VDC is the DC component of the output voltage.
VPEAK is the highest positive excursion of the AC component of the output voltage.
For the circuit shown in Figure 21:
VRMS = (3.6V - 1.8V) + 1.0V/√2 = 2.507VRMS
IRMS can be calculated as:
IRMS ≅ IDC + (IPEAK/√2)
(EQ 3)
Where:
IDC is the DC component of the output current.
IPEAK is the highest positive excursion of the AC component of the output current.
For the circuit shown in Figure 21:
IRMS = (1.8V/32Ω) + (1.0V/32Ω)/√2 = 78.4mARMS
Therefore, for the circuit in Figure 21 the package power dissipation can be calculated as:
PPACKAGEDISS = VRMS IRMS COSθ = 196mW
Adding a coupling capacitor improves the package power dissipation because there is no DC current to the load, as
shown in Figure 22 on page 10.
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