Intel LF80537GG0252M Datasheet download pdf (Page 109)

Datasheet

109

Thermal Specifications and Design Considerations

NOTES:

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

2. Characterized across a temperature range of 50-105°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

* (e

–1)

where I

= saturation current, q = electronic charge, V

= voltage across the transistor

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

temperature (Kelvin).

5.1.2 Intel® Thermal Monitor

The Intel Thermal Monitor helps control the processor temperature by activating the

TCC (Thermal Control Circuit) when the processor silicon reaches its maximum

operating temperature. The temperature at which the Intel Thermal Monitor activates

the TCC is not user configurable. Bus traffic is snooped in the normal manner and

interrupt requests are latched (and serviced during the time that the clocks are on)

while the TCC is active.

With a properly designed and characterized thermal solution, the TCC would only be

activated for very short periods of time when running the most power-intensive

applications. The processor performance impact due to these brief periods of TCC

activation is expected to be minor and hence not detectable. An under-designed

thermal solution that is not able to prevent excessive activation of the TCC in the

anticipated ambient environment may cause a noticeable performance loss and may

affect the long-term reliability of the processor. In addition, a thermal solution that is

significantly under designed may not be capable of cooling the processor even when

the TCC is active continuously.

The Intel Thermal Monitor controls the processor temperature by modulating (starting

and stopping) the processor core clocks or by initiating an Enhanced Intel SpeedStep

Technology transition when the processor silicon reaches its maximum operating

temperature. The Intel Thermal Monitor uses two modes to activate the TCC: automatic

mode and on-demand mode. If both modes are activated, automatic mode takes

precedence.

There are two automatic modes called Intel Thermal Monitor 1 (TM1) and Intel Thermal

Monitor 2 (TM2). These modes are selected by writing values to the MSRs of the

processor. After automatic mode is enabled, the TCC will activate only when the

internal die temperature reaches the maximum allowed value for operation.

When TM1 is enabled and a high temperature situation exists, the clocks will be

modulated by alternately turning the clocks off and on at a 50% duty cycle. Cycle times

are processor speed-dependent and will decrease linearly as processor core frequencies

increase. Once the temperature has returned to a non-critical level, modulation ceases

and TCC goes inactive. A small amount of hysteresis has been included to prevent rapid

Table 28. Thermal Diode Parameters Using Transistor Model

Symbol Parameter Min Typ Max Unit Notes

Forward Bias Current 5 — 200 μA1

Emitter Current 5 — 200 μA1

Transistor Ideality 0.997 1.001 1.008 2, 3, 4

Beta 0.1 0.4 0.5 2, 3

Series Resistance 3.0 4.5 7.0 Ω 2

1 2 ... 104 105 106 107 108 109 110 111 112 113

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Intel LF80537GG0252M Datasheet Page 109

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