LM86 datasheet(18/21 Pages) NSC

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3.0 Application Hints (Continued)

mobile Pentium III processor, 1.008. When a temperature

sensor calibrated for a particular processor type is used with

a different processor type or a given processor type has a

non-ideality that strays from the typical, errors are intro-

duced. Figure 12 shows the minimum and maximum errors

introduced to a temperature sensor calibrated specifically to

the typical value of the processor type it is connected to. The

errors in this figure are attributed only to the variation in

non-ideality from the typical value. In Figure 13 is a plot of

the errors that result from using a temperature sensor cali-

brated for a Pentium II, the LM84, with a typical Pentium 4 or

AMD Athlon MP Model 6.

Temperature errors associated with non-ideality may be re-

duced in a specific temperature range of concern through

use of the offset registers (11h and 12h). Figure 14 shows

how the offset register may be used to compensate for the

non-ideality errors shown in Figure 13. For the case of

non-ideality=1.008, the offset register was set to −0.5˚C

resulting in the calculated residual error as shown in Figure

14. This offset has resulted in an error of less than 0.05˚C for

the temperatures measured in the critical range between 60

to 100˚C. This method yeilds a first order correction factor.

Please send an email to hardware.monitor.team@nsc.com

requesting further information on our recommended setting

of the offset register for different processor types.

10130337

Error Caused by Non-Ideality Factor

FIGURE 12.

10130336

Errors Induced when Temperature Sensor is Not

Calibrated to Typical Non-Ideality

FIGURE 13.

10130338

Compensating for an Untargeted Non-Ideality Factor

FIGURE 14.

LM86 Folha de dados(PDF) 18 Page - National Semiconductor (TI)