N270 datasheet(51/57 Pages) INTEL

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Thermal Specifications and Design Considerations

Datasheet

The processor incorporates three methods of monitoring die temperature: the Digital

Thermal Sensor, Intel Thermal Monitor, and the Thermal Diode. The Intel Thermal

Monitor (detailed in Section 5.2) must be used to determine when the maximum

specified processor junction temperature has been reached.

5.1

Thermal Diode

The processor incorporates an on-die PNP transistor whose base emitter junction is

used as a thermal “diode”, with its collector shorted to ground. The thermal diode can

be read by an off-die analog/digital converter (a thermal sensor) located on the

motherboard or a stand-alone measurement kit. The thermal diode may be used to

monitor the die temperature of the processor for thermal management or

instrumentation purposes but is not a reliable indication that the maximum operating

temperature of the processor has been reached. When using the thermal diode, a

temperature offset value must be read from a processor MSR and applied. See

Section 5.2 for more details. See Section 5.3 for thermal diode usage recommendation

when the PROCHOT# signal is not asserted.

The reading of the external thermal sensor (on the motherboard) connected to the

processor thermal diode signals will not necessarily reflect the temperature of the

hottest location on the die. This is due to inaccuracies in the external thermal sensor,

on-die temperature gradients between the location of the thermal diode and the

hottest location on the die, and time based variations in the die temperature

measurement. Time based variations can occur when the sampling rate of the thermal

diode (by the thermal sensor) is slower than the rate at which the TJ temperature can

change.

Offset between the thermal diode based temperature reading and the Intel Thermal

Monitor reading may be characterized using the Intel Thermal Monitor’s Automatic

mode activation of the thermal control circuit. This temperature offset must be taken

into account when using the processor thermal diode to implement power

management events. This offset is different than the diode Toffset value programmed

into the processor Model Specific Register (MSR).

Table 15 and Table 16 provide the diode interface and specifications. Transistor model

parameters shown in Table 16 provide more accurate temperature measurements

when the diode ideality factor is closer to the maximum or minimum limits. Contact

your external sensor supplier for their recommendation. The thermal diode is separate

from the Thermal Monitor’s thermal sensor and cannot be used to predict the behavior

of the Thermal Monitor.

N270 Datasheet(PDF) 51 Page - Intel Corporation