Typical Applications
CAPACITIVE LOADS
Like most micropower circuits, the LM45 has a limited ability
to drive heavy capacitive loads. The LM45 by itself is able to
drive 500 pF without special precautions. If heavier loads are
anticipated, it is easy to isolate or decouple the load with a
resistor; see
Figure 4.
Or you can improve the tolerance of
capacitance with a series R-C damper from output to
ground; see
Figure 5.
Any linear circuit connected to wires in a hostile environment
can have its performance affected adversely by intense elec-
tromagnetic sources such as relays, radio transmitters, mo-
tors with arcing brushes, SCR transients, etc, as its wiring
can act as a receiving antenna and its internal junctions can
act as rectifiers. For best results in such cases, a bypass ca-
pacitor from V
IN
to ground and a series R-C damper such as
75Ω in series with 0.2 or 1 µF from output to ground, as
shown in
Figure 5,
are often useful.
DS011754-14
FIGURE 7. 4-to-20 mA Current Source (0˚C to +100˚C)
DS011754-8
FIGURE 4. LM45 with Decoupling from Capacitive Load
DS011754-9
FIGURE 5. LM45 with R-C Damper
DS011754-15
FIGURE 8. Fahrenheit Thermometer
DS011754-12
FIGURE 6. Temperature Sensor,
Single Supply, −20˚C to +100˚C
DS011754-16
FIGURE 9. Centigrade Thermometer (Analog Meter)
5
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