ISL28191, ISL28291
12
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FN6156.9
January 26, 2012
Power Dissipation
It is possible to exceed the +125°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 in Equation
1:where:
PDMAXTOTAL is the sum of the maximum power dissipation of
each amplifier in the package (PDMAX)
PDMAX for each amplifier can be calculated in Equation 2: where:
TMAX = Maximum ambient temperature
θJA = Thermal resistance of the package
PDMAX = Maximum power dissipation of 1 amplifier
VS = Supply voltage
IMAX = Maximum supply current of 1 amplifier
VOUTMAX = Maximum output voltage swing of the application
RL = Load resistance
TJMAX
TMAX θJAxPDMAXTOTAL
()
+
=
(EQ. 1)
PDMAX
2*VS ISMAX VS
(
- VOUTMAX)
VOUTMAX
RL
------------------------
×
+
×
=
(EQ. 2)