Intel BX80569QX6850 Datasheet download pdf (Page 90)

Thermal Specifications and Design Considerations

90 Datasheet

5.3 Thermal Diode

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

used as a thermal "diode", with its collector shorted to ground. A thermal sensor

located on the system board may monitor the die temperature of the processor for

thermal management and fan speed control. Table 33,Table 34, and Table 35 provide

the "diode" parameter and interface specifications. Two different sets of "diode"

parameters are listed in Table 33 and Table 34. The Diode Model parameters (Table 33)

apply to traditional thermal sensors that use the Diode Equation to determine the

processor temperature. Transistor Model parameters (Table 34) have been added to

support thermal sensors that use the transistor equation method. The Transistor Model

may provide more accurate temperature measurements when the diode ideality factor

is closer to the maximum or minimum limits. This thermal "diode" is separate from the

Thermal Monitor's thermal sensor and cannot be used to predict the behavior of the

Thermal Monitor.

CONTROL

is a temperature specification based on a temperature reading from the

thermal diode. The value for T

CONTROL

will be calibrated in manufacturing and

configured for each processor. When T

DIODE

is above T

CONTROL

, then T

must be at or

below T

C_MAX

as defined by the thermal profile in Table 29; otherwise, the processor

temperature can be maintained at T

CONTROL

(or lower) as measured by the thermal

diode.

NOTES:

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

2. Characterized across a temperature range of 50 – 80 °C.

3. Not 100% tested. Specified by design characterization.

4. The ideality factor, n, represents the deviation from ideal diode behavior as exemplified by

the diode equation:

= I

* (e

/nkT

–1)

where I

= saturation current, q = electronic charge, V

= voltage across the diode,

k = Boltzmann Constant, and T = absolute temperature (Kelvin).

5. The series resistance, R

, is provided to allow for a more accurate measurement of the

junction temperature. R

, as defined, includes the lands of the processor but does not

include any socket resistance or board trace resistance between the socket and the

external remote diode thermal sensor. R

can be used by remote diode thermal sensors

with automatic series resistance cancellation to calibrate out this error term. Another

application is that a temperature offset can be manually calculated and programmed into

an offset register in the remote diode thermal sensors as exemplified by the equation:

error

= [R

* (N–1) * I

FWmin

] / [nk/q * ln N]

where T

error

= sensor temperature error, N = sensor current ratio, k = Boltzmann

Constant, q = electronic charge.

Table 33. Thermal “Diode” Parameters using Diode Model

Symbol Parameter Min Typ Max Unit Notes

Forward Bias Current 5 — 200 µA 1

n Diode Ideality Factor 1.000 1.009 1.050 - 2, 3, 4

Series Resistance 2.79 4.52 6.24 Ω 2, 3, 5

1 2 ... 85 86 87 88 89 90 91 92 93 94 95 ... 121 122

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