2.0 Serial Bus Timing Diagrams

3.0 Application Hints

To get the expected results when measuring temperature

with an integrated circuit temperature sensor like the LM71,

it is important to understand that the sensor measures its

own die temperature. For the LM71, the best thermal path

between the die and the outside world is through the LM71’s

pins. In the SOT23 package, all the pins on the LM71 will

have an equal effect on the die temperature. Because the

pins represent a good thermal path to the LM71 die, the

LM71 will provide an accurate measurement of the tempera-

ture of the printed circuit board on which it is mounted. There

is a less efficient thermal path between the plastic package

and the LM71 die. If the ambient air temperature is signifi-

cantly different from the printed circuit board temperature, it

will have a small effect on the measured temperature.

In probe-type applications, the LM71 can be mounted inside

a sealed-end metal tube, and can then be dipped into a bath

or screwed into a threaded hole in a tank. As with any IC, the

LM71 and accompanying wiring and circuits must be kept

insulated and dry, to avoid leakage and corrosion. This is

especially true if the circuit may operate at cold temperatures

where condensation can occur. Printed-circuit coatings and

varnishes such as Humiseal and epoxy paints or dips are

often used to insure that moisture cannot corrode the LM71

or its connections.

20031714

a) Reading Continuous Conversion - Single Eight-Bit Frame

20031715

b) Reading Continuous Conversion - Two Eight-Bit Frames

20031718

c) Writing Shutdown Control

FIGURE 7. Timing Diagrams

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