LM70 datasheet(11/14 Pages) NSC

11 / 14 page

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 LM70,

it is important to understand that the sensor measures its

own die temperature. For the LM70, the best thermal path

between the die and the outside world is through the LM70’s

pins. In the MSOP-8 package the ground pin is connected to

the back side of the LM70 die and thus has the most effect

on the die temperature. Although the other pins will also

have some effect on the LM70die temperature and therefore

should not be discounted. The LM70 will provide an accurate

measurement of the temperature of the printed circuit board

on which it is mounted, because the pins represent a good

thermal path to the die. A less efficient thermal path exists

between the plastic package and the LM70 die. If the ambi-

ent air temperature is significantly different from the printed

circuit board temperature, it will have a small effect on the

measured temperature.

In probe-type applications, the LM70 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

LM70 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 LM70

or its connections.

10122314

a) Reading Continuous Conversion - Single Eight-Bit Frame

10122315

b) Reading Continuous Conversion - Two Eight-Bit Frames

10122318

c) Writing Shutdown Control

FIGURE 7. Timing Diagrams

LM70 Scheda tecnica(PDF) 11 Page - National Semiconductor (TI)