Datasheet

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       
    
SLVS230G − SEPTEMBER 1999 − REVISED JANUARY 2004
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18
APPLICATION INFORMATION
POWER DISSIPATION AND JUNCTION TEMPERATURE
Specified regulator operation is assured to a junction temperature of 125°C; the maximum junction temperature should be
restricted to 125°C under normal operating conditions. This restriction limits the power dissipation the regulator can handle
in any given application. To ensure the junction temperature is within acceptable limits, calculate the maximum allowable
dissipation, P
D(max)
, and the actual dissipation, P
D
, which must be less than or equal to P
D(max)
.
The maximum-power-dissipation limit is determined using the following equation:
P
D(max)
+
T
J
max * T
A
R
qJA
Where:
T
J
max is the maximum allowable junction temperature.
T
A
is the ambient temperature.
R
θJA
is the thermal resistance junction-to-ambient for the package, and is calculated as
1
derating factor
from the dissipation rating tables.
The regulator dissipation is calculated using:
P
D
+
ǒ
V
I
* V
O
Ǔ
I
O
Power dissipation resulting from quiescent current is negligible. Excessive power dissipation will trigger the thermal
protection circuit.