MC78FC00 Datasheet, PDF (4/8 Pages) Motorola, Inc – MICROPOWER ULTRA.LOW QUIESCENT CURRENT VOLTAGE REGULATORS

MC78FC00 Series
APPLICATIONS INFORMATION
Introduction
The MC78FC00 micropower voltage regulators are
specifically designed with internal current limiting and low
quiescent current making them ideal for battery powered
applications. An input bypass capacitor is recommended if
the regulator is located an appreciable distance (≥ 4 inches)
from the input voltage source. These regulators require
0.1 µF capacitance between the output terminal and ground
for stability. Most types of aluminum, tantalum or multilayer
ceramic will perform adequately. Solid tantalums or other
appropriate capacitors are recommended for operation
below 25°C. The bypass capacitors should be mounted with
the shortest possible leads or track lengths directly across the
regulator input and output terminals.
With economical electrolytic capacitors, cold temperature
operation can pose a serious stability problem. As the
electrolyte freezes, around –30°C, the capacitance will
decrease and the equivalent series resistance (ESR) will
increase drastically, causing the circuit to oscillate. Quality
electrolytic capacitors with extended temperature ranges of
–40° to +85°C are readily available. Solid tantalum
capacitors may be the better choice if small size is a
requirement. However, a maximum ESR limit of 3.0 Ω must
be observed over temperature to maintain stability.
Figure 6 is a typical circuit application. Figure 7 is a
current boost circuit which can deliver more than 600 mA.
The circuit has no current limiting and the external transistor
must be rated for the expected power dissipation.
V_in
0.1 µF
2
3
MC78FC00
1
V_O
0.1 µF
Gnd
Gnd
Figure 6. Typical Application
V_in
10 µF
Gnd
MJD32C
.033 µF
2
3
MC78FC00
100
1
0.1 µF
V_O
0.1 µF
Gnd
Figure 7. Current Boost Circuit
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