R1

4.1V

R3

R2

0.1 PF

U3

LM4040

R4

V+

+

-

U1

LM20

V+

U2

(High = overtemp alarm)

R1 + R2||R3

(4.1)R2

R2 + R1||R3

(4.1)R2||R3

LM7211

LM20

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SNIS106P – DECEMBER 1999 – REVISED FEBRUARY 2013

Figure 7. LM20 with Filter for Noisy Environment and Capacitive Loading Greater Than 300 pF

NOTE

Either placement of resistor as shown above is just as effective.

LM20 DSBGA Light Sensitivity

Exposing the LM20 DSBGA package to bright sunlight may cause the output reading of the LM20 to drop by

1.5V. In a normal office environment of fluorescent lighting the output voltage is minimally affected (less than a

millivolt drop). In either case it is recommended that the LM20 DSBGA be placed inside an enclosure of some

type that minimizes its light exposure. Most chassis provide more than ample protection. The LM20 does not

sustain permanent damage from light exposure. Removing the light source will cause LM20's output voltage to

recover to the proper value.

APPLICATION CIRCUITS

Figure 8. Centigrade Thermostat

Figure 9. Conserving Power Dissipation with Shutdown

Copyright © 1999–2013, Texas Instruments Incorporated

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