Typical Applications

CAPACITIVE LOADS

Like most micropower circuits, the LM35 has a limited ability

to drive heavy capacitive loads. The LM35 by itself is able to

drive 50 pf without special precautions. If heavier loads are

anticipated, it is easy to isolate or decouple the load with a

resistor; see

Figure 3. Or you can improve the tolerance of

capacitance with a series R-C damper from output to

ground; see

Figure 4.

When the LM35 is applied with a 200

Ω load resistor as

shown in

Figure 5, Figure 6 or Figure 8 it is relatively immune

to wiring capacitance because the capacitance forms a by-

pass from ground to input, not on the output. However, as

with any linear circuit connected to wires in a hostile envi-

ronment, its performance can be affected adversely by in-

tense electromagnetic sources such as relays, radio trans-

mitters, motors 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 capacitor from V

IN to ground and a series R-C

damper such as 75

Ω in series with 0.2 or 1 µF from output to

ground are often useful. These are shown in

Figure 13,

Figure 14, and Figure 16.

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FIGURE 3. LM35 with Decoupling from Capacitive Load

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FIGURE 4. LM35 with R-C Damper

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FIGURE 5. Two-Wire Remote Temperature Sensor

(Grounded Sensor)

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FIGURE 6. Two-Wire Remote Temperature Sensor

(Output Referred to Ground)

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FIGURE 7. Temperature Sensor, Single Supply, −55˚ to

+150˚C

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FIGURE 8. Two-Wire Remote Temperature Sensor

(Output Referred to Ground)

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FIGURE 9. 4-To-20 mA Current Source (0˚C to +100˚C)