ISL70218SEH
Power Dissipation
It is possible to exceed the +150°C maximum junction
temperatures under certain load and power supply conditions. It
is therefore important to calculate the maximum junction
temperature (TJMAX) for all applications to determine if power
supply voltages, load conditions, or package type need to be
modified to remain in the safe operating area. These parameters
are related using Equation 1:
(EQ. 1)
T
= T
+ θ xPD
MAX JA MAXTOTAL
JMAX
where
• PDMAXTOTAL is the sum of the maximum power dissipation of
each amplifier in the package (PDMAX
)
• TMAX = Maximum ambient temperature
• ΘJA = Thermal resistance of the package
PDMAX for each amplifier can be calculated using Equation 2:
V
OUTMAX
R
L
(EQ. 2)
------------------------
PD
= V × I
+ (V - V ) ×
OUTMAX
MAX
S
qMAX
S
where
• PDMAX = Maximum power dissipation of one amplifier
• VS = Total supply voltage
• IqMAX = Maximum quiescent supply current of one amplifier
• VOUTMAX = Maximum output voltage swing of the application
• RL = Load resistance
FN7957.1
August 24, 2012
17
INTERSIL [ Intersil ]
