MC79L00A Series
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5
APPLICATIONS INFORMATION
Design Considerations
The MC79L00A Series of fixed voltage regulators are
designed with Thermal Overload Protections that shuts
down the circuit when subjected to an excessive power
overload condition, Internal Short Circuit Protection that
limits the maximum current the circuit will pass.
In many low current applications, compensation
capacitors are not required. However, it is recommended
that the regulator input be bypassed with a capacitor if the
regulator is connected to the power supply filter with long
wire length, or if the output load capacitance is large. An
input bypass capacitor should be selected to provide good
high−frequency characteristics to insure stable operation
under all load conditions. A 0.33 mF or larger tantalum,
mylar, or other capacitor having low internal impedance at
high frequencies should be chosen. The bypass capacitor
should be mounted with the shortest possible leads directly
across the regulator’s input terminals. Normally good
construction techniques should be used to minimize ground
loops and lead resistance drops since the regulator has no
external sense lead. Bypassing the output is also
recommended.
Figure 2. Positive and Negative Regulator Figure 3. Standard Application
+V
in
+V
O
0.1mF
-V
in
-V
O
0.33mF
MC78LXX
MC79LXX
0.1mF
0.33mF
Input Output
C
O
**
0.1mF
C
I
*
0.33mF
MC79LXX
A common ground is required between the input and the output
voltages. The input voltage must remain typically 2.0 V above
the output voltage even during the low point on the ripple voltage.
* C
I
is required if regulator is located an appreciable
* distance from the power supply filter
** C
O
improves stability and transient response.
