Intel N455 AU80610006237AA User Manual

66

Datasheet

 provide the diode interface and specifications. Transistor 

model parameters shown in 

 providing 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.

NOTES:
1.

Intel does not support or recommend operation of the thermal diode under reverse bias. 

2.

Characterized across a temperature range of 50–100°C.

3.

Not 100% tested. Specified by design characterization.

4.

The ideality factor, nQ, represents the deviation from ideal transistor model behavior as 
exemplified by the equation for the collector current:

I

C

 = I

S

 * (e 

qV

BE

/n

Q

kT

 –1)

where I

S

 = saturation current, q = electronic charge, V

BE

 = voltage across the transistor 

base emitter junction (same nodes as VD), k = Boltzmann Constant, and T = absolute 

temperature (Kelvin).

5.

The series resistance, R

T

, provided in the Diode Model Table (

more accurate readings as needed. 

When calculating a temperature based on the thermal diode measurements, a number 
of parameters must be either measured or assumed. Most devices measure the diode 
ideality and assume a series resistance and ideality trim value, although are capable of 
also measuring the series resistance. Calculating the temperature is then accomplished 
using the equations listed under 

. In most sensing devices, an expected 

value for the diode ideality is designed-in to the temperature calculation equation. If 
the designer of the temperature sensing device assumes a perfect diode, the ideality 
value (also called n

trim

) will be 1.000. Given that most diodes are not perfect, the 

designers usually select an n

trim

 value that more closely matches the behavior of the 

diodes in the processor. If the processor diode ideality deviates from that of the n

trim

, 

each calculated temperature will be offset by a fixed amount. This temperature offset 
can be calculated with the equation:

THRMDA_1

D30

Thermal diode anode

THRMDC_1

E30

Thermal diode cathode

IFW

Forward Bias Current

5

200

μA

1

IE

Emitter Current

5

200

μA

1

nQ

Transistor Ideality

0.997

1.001

1.015

2,3,4

Beta

0.25

0.65

2,3

RT

Series Resistance

2.79

4.52

6.24

Ω

2,5