MC79LXXA Datasheet, PDF (8/12 Pages) Fairchild Semiconductor – 3-Terminal 0.1A Negative Voltage Regulator

MC79LXXA/LM79LXXA
Typical Application
Design Considerations
The MC79LXXA/LM79LXXA Series of fixed voltage regulators are designed with Thermal Overload Protection 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 lengths, 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 0.33µF 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.
LM78LXXA
MC78LXXA
I
MC79LXXA
LM79LXXA
LM79LXXA
MC79LXXA
Figure 1. Positive And Negative Regulator
Figure 2. Typical Application
A common ground is required between the Input and the output voltages. The input voltage must remain typically 2.0V above
the output voltage even during the low point on the input ripple voltage.
* C1 is required if regulator is located an appreciable distance from power supply filter.
* CO improves stability and transient response.
8