Datasheet

Table Of Contents

LM63

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SNAS190E –SEPTEMBER 2002–REVISED MAY 2013

The voltage seen by the LM63 also includes the I

×R

voltage drop across the internal series resistance of the

Pentium 4 processor’s thermal diode. The non-ideality factor, η, is the only other parameter not accounted for

and depends on the diode that is used for measurement. Since ΔV

is proportional to both η and T, the

variations in η cannot be distinguished from variations in temperature. Since the temperature sensor does not

control the non-ideality factor, it will directly add to the inaccuracy of the sensor.

For the Intel Pentium 4 and Mobile Pentium 4 Processor-M processors Intel specifies a ±0.1% variation in η from

part to part. As an example, assume that a temperature sensor has an accuracy specification of ±1%°C at room

temperature of 25°C and process used to manufacture the diode has a non-ideality variation of ±0.1%. The

resulting accuracy will be:

ACC

= ±1°C + (±0.1% of 298°K) = ±1.3°C (9)

The additional inaccuracy in the temperature measurement caused by η, can be eliminated if each temperature

sensor is calibrated with the remote diode that it will be paired with. Refer to the processor datasheet for the non-

ideality factor.

COMPENSATING FOR DIODE NON-IDEALITY

In order to compensate for the errors introduced by non-ideality, the temperature sensor is calibrated for a

particular processor. Texas Instruments temperature sensors are always calibrated to the typical non-ideality of a

particular processor type.

The LM63 is calibrated for the non-ideality of the 0.13 micron Intel Pentium 4 and Mobile Pentium 4 Processor-M

processors.

When a temperature sensor, calibrated for a specific type of processor is used with a different processor type or

a given processor type has a non-ideality that strays form the typical value, errors are introduced.

Temperature errors associated with non-ideality may be introduced in a specific temperature range of concern

through the use of the Temperature Offset Registers 11

HEX

and 12

HEX

The user is encouraged to send an e-mail to hardware.monitor.team@ti.com to further request information on

our recommended setting of the offset register for different processor types.

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