GM78L00 Datasheet, PDF (7/7 Pages) List of Unclassifed Manufacturers – 100 mA POSITIVE VOLTAGE REGULATORS

PRELIMINARY
GM78L00
APPLICATION INFORMATION
100 mA POSITIVE VOLTAGE REGULATORS
Design Considerations
The GM78L series regulators have thermal overload
protection from excessive power, internal short-circuit
protection which limits each circuit’s maximum current,
and output transistor safe-area protection for reducing
the output current as the voltage across each pass
transistor is increased.
Although the internal power dissipation is limited, the
junction temperature must be kept below the maximum
specified temperature (125°C) in order to meet data
sheet specifications.
Thermal Considerations
The TO-92 molded package is capable of unusually
high power dissipation due to the lead frame design.
However, its thermal capabilities are generally
overlooked because of a lack of understanding of the
thermal paths from the semiconductor junction to
ambient temperature.
While thermal resistance is normally specified for the
device mounted 1 cm above an infinite heat sink, very
little has been mentioned of the options available to
improve on the conservatively rated thermal capability.
An explanation of the thermal paths of the TO-92 will
allow the designer to determine the thermal stress he
is applying in any given application.
The TO-92 Package
The TO-92 package thermal paths are complex. In
addition to the path through the molding compound to
ambient temperature, there is another path through the
leads, in parallel with the case path, to ambient
temperature, as shown in Figure 1.
The total thermal resistance in this model is then:
θ_JA =
( θ_JA + θ_CA) ( θ_JL + θ_LA)
θ_JA + θ_CA + θ_JL + θ_LA
Where:
θ_JC = thermal resistance of the case between the
regulator die and a point on the case directly above the
die location.
θ_CA = thermal resistance between the case and air at
ambient temperature.
θ_JL = thermal resistance from regulator die through the
input lead to a point ¹/₁₆ inch below the regulator case.
θ_LA = total thermal resistance of the input/output ground
leads to ambient temperature.
θ_JA = junction to ambient thermal resistance.
FIGURE 1. TO-92 Thermal Equivalent Circuit
T_J
θ_JC
θ_JL
θCA
θ_LA
TA
P_E (W)
ORDERING INFORMATION
GM78L00
OUTPUT VOLTAGE
5V
6V
8V
9V
10V
12V
15V
18V
24V
TO-92
GM78L05-T92
GM78L06-T92
GM78L08-T92
GM78L09-T92
GM78L10-T92
GM78L12-T92
GM78L15-T92
GM78L18-T92
GM78L24-T92
PACKAGE
SOT-89
GM78L05-ST89
GM78L06-ST89
GM78L08-ST89
GM78L09-ST89
GM78L10-ST89
GM78L12-ST89
GM78L15-ST89
GM78L18-ST89
GM78L24-ST89
SOP 8
GM78L05-S8
GM78L06-S8
GM78L08-S8
GM78L09-S8
GM78L10-S8
GM78L12-S8
GM78L15-S8
GM78L18-S8
GM78L24-S8
Revision 1, May 2002
6
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