Intel Atom Processor N270 AU80586GE025D Data Sheet

Datasheet  

 51 

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. 

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 T

J

 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 T

offset

 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.