Title: Temperature-based cooling device controller apparatus and method
Abstract: A temperature-based cooling device controller is implemented in an integrated circuit such as a microprocessor. The temperature-based cooling device controller includes a register to store a threshold temperature value, a thermal sensor, and clock adjustment logic to activate a cooling device in response to the thermal sensor indicating that the threshold temperature value has been exceeded. In a microprocessor implementation, the microprocessor contains a plurality of thermal sensors each placed in one of a plurality of different locations across the integrated circuit and an averaging mechanism to calculate an average temperature from the plurality of thermal sensors. Threshold adjustment logic increases the threshold temperature value to a new threshold temperature value in response to the thermal sensor indicating that the threshold temperature value has been exceeded. Threshold adjustment logic further lowers the new threshold temperature to detect decreases in temperature.
Patent Number: 6,975,047 Issued on 12/13/2005 to Pippin
| Inventors:
|
Pippin; Jack D. (Portland, OR)
|
| Assignee:
|
Intel Corporation (Santa Clara, CA)
|
| Appl. No.:
|
464284 |
| Filed:
|
June 18, 2003 |
| Current U.S. Class: |
307/117; 361/103; 327/512; 374/173 |
| Intern'l Class: |
H01H 035/00 |
| Field of Search: |
307/117
361/103
327/512
374/173
|
References Cited [Referenced By]
U.S. Patent Documents
| 3980505 | Sep., 1976 | Buckley.
| |
| 4432031 | Feb., 1984 | Premerlani.
| |
| 4442972 | Apr., 1984 | Sahay et al.
| |
| 4488824 | Dec., 1984 | Salem.
| |
| 4557223 | Dec., 1985 | N Gueyen.
| |
| 4591855 | May., 1986 | Blackburn.
| |
| 4669205 | Jun., 1987 | Smathers.
| |
| 4680527 | Jul., 1987 | Benenati et al.
| |
| 4740664 | Apr., 1988 | Payne et al.
| |
| 4751405 | Jun., 1988 | Bufano, Jr. et al.
| |
| 4779161 | Oct., 1988 | DeShazo, Jr.
| |
| 4787007 | Nov., 1988 | Matsumura et al.
| |
| H562 | Dec., 1988 | Trachier et al.
| |
| 4789819 | Dec., 1988 | Nelson.
| |
| 4799176 | Jan., 1989 | Cacciatore.
| |
| 4807144 | Feb., 1989 | Joehlin et al.
| |
| RE32960 | Jun., 1989 | Levine.
| |
| 4848090 | Jul., 1989 | Peters.
| |
| 4851987 | Jul., 1989 | Day.
| |
| 4893097 | Jan., 1990 | Zwack.
| |
| 4903106 | Feb., 1990 | Fukunaga et al.
| |
| 4924112 | May., 1990 | Anderson et al.
| |
| 4935864 | Jun., 1990 | Schmidt et al.
| |
| 4970497 | Nov., 1990 | Broadwater.
| |
| 5008771 | Apr., 1991 | Palara.
| |
| 5025248 | Jun., 1991 | Bergeron.
| |
| 5064296 | Nov., 1991 | Huijsing et al.
| |
| 5077491 | Dec., 1991 | Heck et al.
| |
| 5085526 | Feb., 1992 | Sawtell et al.
| |
| 5087870 | Feb., 1992 | Salesky et al.
| |
| 5105366 | Apr., 1992 | Beckey.
| |
| 5149199 | Sep., 1992 | Kinoshita.
| |
| 5170344 | Dec., 1992 | Berton et al.
| |
| 5189314 | Feb., 1993 | Georgiou et al.
| |
| 5195827 | Mar., 1993 | Audy et al.
| |
| 5201862 | Apr., 1993 | Pettitt.
| |
| 5253938 | Oct., 1993 | Stixrud.
| |
| 5255149 | Oct., 1993 | Matsuo.
| |
| 5283631 | Feb., 1994 | Koerner et al.
| |
| 5285237 | Feb., 1994 | Parulski.
| |
| 5285347 | Feb., 1994 | Fox.
| |
| 5287292 | Feb., 1994 | Kenny et al.
| |
| 5291607 | Mar., 1994 | Ristic et al.
| |
| 5325286 | Jun., 1994 | Weng et al.
| |
| 5359234 | Oct., 1994 | Atriss et al.
| |
| 5359236 | Oct., 1994 | Giordano et al.
| |
| RE34789 | Nov., 1994 | Fraden.
| |
| 5379230 | Jan., 1995 | Morikawa.
| |
| 5381700 | Jan., 1995 | Grosskopf, Jr.
| |
| 5422832 | Jun., 1995 | Moyal.
| |
| 5424764 | Jun., 1995 | Yamaguchi et al.
| |
| 5440305 | Aug., 1995 | Signore et al.
| |
| 5444637 | Aug., 1995 | Smesny et al.
| |
| 5451892 | Sep., 1995 | Bailey.
| |
| 5453682 | Sep., 1995 | Hinrichs et al.
| |
| 5455510 | Oct., 1995 | Nelson.
| |
| 5477417 | Dec., 1995 | Ohmori.
| |
| 5483102 | Jan., 1996 | Neal et al.
| |
| 5485127 | Jan., 1996 | Bertoluzzi et al.
| |
| 5490059 | Feb., 1996 | Mahalingaiah et al.
| |
| 5560017 | Sep., 1996 | Barrett et al.
| |
| 5586270 | Dec., 1996 | Rotier et al.
| |
| 5596514 | Jan., 1997 | Maher et al.
| |
| 5612672 | Mar., 1997 | Ino et al.
| |
| 5664201 | Sep., 1997 | Ikedea.
| |
| 5688116 | Nov., 1997 | Kobayashi et al.
| |
| 5723998 | Mar., 1998 | Saito et al.
| |
| 5764601 | Jun., 1998 | Murakami et al.
| |
| 5798667 | Aug., 1998 | Herbert.
| |
| 5805403 | Sep., 1998 | Chemla.
| |
| 5808438 | Sep., 1998 | Jeffrey.
| |
| 5838578 | Nov., 1998 | Pippin.
| |
| 5848486 | Dec., 1998 | Mitchell et al.
| |
| 5870267 | Feb., 1999 | Kitano.
| |
| 5902044 | May., 1999 | Pricer.
| |
| 6006169 | Dec., 1999 | Sandhu et al.
| |
| 6029119 | Feb., 2000 | Atkinson.
| |
| 6055489 | Apr., 2000 | Beatty et al.
| |
| 6061221 | May., 2000 | Tihanyi.
| |
| 6078209 | Jun., 2000 | Linoff.
| |
| 6079626 | Jun., 2000 | Hartman.
| |
| 6094026 | Jul., 2000 | Cameron.
| |
| 6112164 | Aug., 2000 | Hobson.
| |
| 6134667 | Oct., 2000 | Suzuki et al.
| |
| 6140860 | Oct., 2000 | Sandhu et al.
| |
| 6172342 | Jan., 2001 | Khafagy et al.
| |
| 6194858 | Feb., 2001 | Chen.
| |
| 6215405 | Apr., 2001 | Handley et al.
| |
| 6216235 | Apr., 2001 | Thomas et al.
| |
| 6225851 | May., 2001 | Descombes.
| |
| 6233190 | May., 2001 | Cooper et al.
| |
| 6272313 | Aug., 2001 | Arsenault et al.
| |
| 6276202 | Aug., 2001 | Latarius.
| |
| 6285245 | Sep., 2001 | Watanabe.
| |
| 6321175 | Nov., 2001 | Nagaraj.
| |
| 6336080 | Jan., 2002 | Atkinson.
| |
| 6361466 | Mar., 2002 | Kyrtsos.
| |
| 6363490 | Mar., 2002 | Senyk.
| |
| 6375624 | Apr., 2002 | Uber et al.
| |
| 6388853 | May., 2002 | Balakrishnan et al.
| |
| 6393374 | May., 2002 | Rankin et al.
| |
| 6403036 | Jun., 2002 | Rodgers et al.
| |
| 6412294 | Jul., 2002 | Kimura et al.
| |
| 6442500 | Aug., 2002 | Kim.
| |
| 6442700 | Aug., 2002 | Cooper.
| |
| 6446213 | Sep., 2002 | Yamaki.
| |
| 6452291 | Sep., 2002 | Erickson et al.
| |
| 6457135 | Sep., 2002 | Cooper.
| |
| 6463396 | Oct., 2002 | Nishigaki.
| |
| 6470289 | Oct., 2002 | Peters et al.
| |
| 6484117 | Nov., 2002 | Wohlfarth.
| |
| 6487668 | Nov., 2002 | Thomas et al.
| |
| 6501776 | Dec., 2002 | Numai.
| |
| 6516781 | Feb., 2003 | Weisman.
| |
| 2002/0105372 | Aug., 2002 | Balakrishnan et al.
| |
| Foreign Patent Documents |
| 3516989 | May., 1985 | DE.
| |
| 0523736 | Jan., 1993 | EP.
| |
| 0683558 | Nov., 1995 | EP.
| |
| 0821459 | Jan., 1998 | EP.
| |
| 0821459 | Jan., 1998 | EP.
| |
| 1093010 | Apr., 1989 | JP.
| |
| 10-93010 | Apr., 1989 | JP.
| |
| 1148769 | Jun., 1989 | JP.
| |
| 11-48769 | Jun., 1989 | JP.
| |
Other References
Chin, Shu-Yuan and Chung-Yu Wu, A New Type of Curvature-Compensated CMOS Bandgap
Voltage References, VLSITSA, 1991, pps. 398-402.
Ferro, Marco, Franco Salerno and Rinaldo Castello, "A Floating CMOS Bandgap Voltage
Reference for Differential Applications", IEEE: Journal of Solid-State Circuits,
vol. 24, No. 3, Jun. 1989, pps. 690-697.
Salminen, O. and K. Halonen, "The Higher Order Temperature Compensation of Bandgap
Voltage References", IEEE, 1992, pps. 1388-1391.
Allen and Holberg, "CMOS Analog Circuit Design", H.P.W., pp. 539-549, 1987.
Sanchez et al., "Thermal Management System for High Peformance PowerPC Microprocessors",
pps. 325-330, 1997.
Intel Corporation, "Advanced Power Management (APM)- BIOS Interface Specification,"
Revision 1.2, Feb. 1996.
The Thomson Corporation, IBM Technical Disclosure Bulletin, "High Power LSI Performance
Optimizer", pp. 324-325, Jan. 1991.
Dynamic Power Management by Clock Speed Variation IBM Technical Disclosure Bulletin,
vol. 32, No. 88, Jan. 1990.
Automatically Controlled Air Cooling System for Small Machines, IBM Technical
Disclosure Bulletin, Jan. 1982.
|
Primary Examiner: DeBeradinis; Robert L.
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier & Neustadt, P.C.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of prior application Ser. No. 09/707,860,
filed Nov. 7, 2000 now U.S. Pat. No. 6,630,754, which is a divisional of prior
application Ser. No. 09/093,988 filed Jun. 8, 1998 now abandoned, which is a continuation
of prior application Ser. No. 08/660,016, filed Jun. 6, 1996, issued as U.S. Pat.
No. 5,838,578 on Nov. 17, 1998, which is a continuation of prior application Ser.
No. 08/124,980, filed Sep. 21, 1993 now abandoned, all entitled "Method and Apparatus
for Programmable Thermal Sensor for an Integrated Circuit" and all assigned to
the assignee of the present application.
Claims
1. An integrated circuit (IC) comprising:
a register incorporated into the IC to store a threshold temperature value;
a thermal sensor incorporated into the IC; and
cooling activation logic incorporated into the IC to activate an active cooling
device in response to the thermal sensor indicating that the threshold temperature
value has been exceeded.
2. The integrated circuit of claim 1 further comprising:
threshold adjustment logic incorporated into the IC to increase the threshold
temperature value to a new threshold temperature value in response to the thermal
sensor indicating that the threshold temperature value has been exceeded.
3. The integrated circuit of claim 2 wherein the threshold adjustment logic is
further to increase the new threshold temperature in response to the thermal sensor
indicating that the new threshold temperature has been exceeded.
4. The integrated circuit of claim 3 wherein the threshold adjustment logic is
further to lower the new threshold temperature to detect decreases in temperature.
5. The integrated circuit of claim 1 wherein the cooling system logic is to activate
the active cooling device after a predetermined duration.
6. The integrated circuit of claim 1 wherein the cooling system logic is to deactivate
the active cooling device in response to the thermal sensor indicating that the
sensed temperature is less than the threshold temperature.
7. The integrated circuit of claim 1 wherein the thermal sensor comprises a plurality
of thermal sensors incorporated into the IC and placed across the integrated circuit
and an averaging mechanism incorporated into the IC to calculate an average temperature
from the plurality of thermal sensors.
8. The integrated circuit of claim 1 further comprising an interrupt handler
to display information regarding the sensed temperature to a user of the integrated circuit.
9. The integrated circuit of claim 1 further comprising interrupt logic to generate
a first interrupt if the calculated average temperature exceeds a first threshold
and a second interrupt if the calculated average temperature exceeds a second threshold.
10. The integrated circuit of claim 1 wherein the cooling system logic executes
instructions to activate the active cooling device of the integrated circuit in
response to the thermal sensor.
11. The integrated circuit of claim 1 wherein the cooling system logic executes
instructions to provide closed loop control of the integrated circuit active cooling
device, thereby automatically reducing the temperature when overheating occurs.
12. The integrated circuit of claim 1 further comprising interrupt logic to activate
an active cooling device in response to the thermal sensor.
13. A method comprising:
storing a threshold temperature value in a register incorporated into an integrated
circuit (IC);
sensing the temperature of the IC using a sensor incorporated into the IC; and
activating an active cooling device for the integrated circuit in response to
the sensed temperature exceeding the threshold temperature value.
14. The method of claim 13 further comprising:
increasing the threshold temperature value to a new threshold temperature value
in response to the sensed temperature exceeding the threshold temperature value.
15. The method of claim 13 further comprising increasing the new threshold temperature
in response to the sensed temperature exceeding the threshold temperature value.
16. The method of claim 13 further comprising lowering the new threshold temperature
to detect decreases in temperature.
17. The method of claim 13 further comprising activating the active cooling device
after a predetermined duration.
18. The method of claim 13 further comprising deactivating the active cooling
device in response to the sensed temperature being less than the threshold temperature.
19. The method of claim 13 further comprising displaying information regarding
the sensed temperature to a user of the integrated circuit.
20. The method of claim 13 further comprising executing instructions to activate
the active cooling device of the integrated circuit in response to the sensed temperature.
21. The method of claim 13 further comprising executing instructions to provide
closed loop control of the active cooling device, thereby automatically reducing
the temperature when overheating occurs.
22. A computer system comprising:
an active cooling device;
a microprocessor comprising:
a register incorporated into the microprocessor, the register storing a register
value corresponding to a threshold temperature;
a programmable thermal sensor incorporated into the microprocessor, the thermal
sensor receiving the register value, wherein the programmable thermal sensor generates
a first interrupt signal if a microprocessor temperature exceeds the threshold
temperature, and wherein the active cooling device is activated in response to
the interrupt signal.
23. The computer system of claim 22 wherein the active cooling device comprises
a fan.
24. The computer system of claim 22 further comprising clock circuitry incorporated
into the microprocessor for providing a clock signal for the microprocessor, wherein
a frequency of the clock signal is reduced in response to the first interrupt signal.
25. The computer system of claim 24 wherein the clock circuitry further comprises:
a first clock;
a frequency divider coupled to the first clock to provide the clock signal, the
frequency divider reducing a frequency of the clock signal in response to the interrupt
signal; and
a second clock circuit coupled to provide the clock signal to the microprocessor.
26. The computer system of claim 25 wherein the clock circuitry further comprises
a phase locked loop.
27. The computer system of claim 25 wherein the microprocessor further comprises:
a processor unit coupled to the second clock circuit, wherein the processor unit
executes instructions to vary the activation of the active cooling device in response
to the first interrupt signal.
28. The computer system of claim 22 wherein the thermal sensor comprises:
a current source;
a voltage reference coupled to the current source and incorporated into the microprocessor
to provide a bandgap reference voltage, wherein the bandgap reference voltage is
substantially constant over a range of temperatures;
programmable circuitry incorporated into the microprocessor, the programmable
circuitry providing an output voltage that varies with the microprocessor temperature
and in accordance with the register value; and
a comparator incorporated into the microprocessor, wherein the comparator generates
the first interrupt signal if a difference between the output voltage and the bandgap
reference voltage indicates that the threshold temperature has been exceeded.
29. The computer system of claim 28 wherein the programmable circuitry further comprises:
a transistor coupled to the current source to provide the output voltage, a gain
ratio of the output voltage to a junction voltage of the transistor controlled
by a transistor bias, wherein the junction voltage varies in accordance with a
junction temperature of the transistor, the junction temperature corresponding
to the microprocessor temperature; and
a bias circuit providing the transistor bias to control the gain ratio, wherein
the output voltage varies with the microprocessor temperature in accordance with
the register value.
30. The computer system of claim 29 wherein the bias circuit further comprises
binary weighted resistors.
31. The computer system of claim 22 wherein the microprocessor programs the register
with another value corresponding to another threshold temperature in response to
the first interrupt signal.
32. The computer system of claim 22 wherein the processor executes instructions
to provide closed loop control of the active cooling device, thereby automatically
reducing the temperature when overheating occurs.
Description
FIELD OF THE INVENTION
The present invention relates to thermal sensing, and more specifically to methods
and apparatus for a programmable thermal sensor in an integrated circuit.
ART BACKGROUND
Advances in silicon process technology has lead to the development of increasingly
larger die sizes for integrated circuits. The large dies sizes permit integration
of millions of transistors on a single die. As die sizes for integrated circuits
become larger, the integrated circuits consume more power. In addition, advances
in microprocessor computing require execution of a large number of instructions
per second. To execute more instructions per second, the microprocessor circuits
operate at an increased clock frequency. Therefore, a microprocessor containing
over one million transistors may consume over 30 watts of power. With large amounts
of power being dissipated, cooling becomes a problem.
Typically, integrated circuits and printed circuit boards are cooled by
either active or passive cooling devices. A passive cooling device, such as a heat
sink mounted onto an integrated circuit, has a limited capacity to dissipate heat.
An active cooling device, such as a fan, is used to dissipate larger amounts of
heat. Although a fan cooling system dissipates heat, there are several disadvantages
associated with such a system. Traditionally, fans cool integrated circuits by
air convection circulated by a fan. However, when a fan is used in conjunction
with a high density multi-chip computer system, a large volume of air is required
for cooling thereby necessitating powerful blowers and large ducts. The powerful
blowers and large ducts implemented in the computer occupy precious space and are
too noisy. The removal of a cover or other casing may result in a disturbance of
air flow causing the fan cooling system to fail. In addition, the fan cooling system
is made up of mechanical parts that have a mean time between failure (MTBF) specification
less than a typical integrated circuit. Furthermore, fan cooling systems introduce
noise and vibration into the system.
In addition to cooling systems, thermal sensors are implemented to track the
temperature
of an integrated circuit or electronic system. Typically, thermal sensors consist
of a thermocouple which is directly attached to a heat sink. In more sophisticated
thermal sensing systems, a diode and external analog circuitry are used. In operation,
the voltage/current characteristics of the diode change depending upon the temperature
of the integrated circuit, and the external analog circuitry measures the voltage
or current characteristics of the diode. The additional analog circuitry is complex
and difficult to implement. In addition, employing the analog circuitry results
in a thermal time delay degrading the accuracy of such a configuration. Moreover,
external analog circuitry for sensing the voltage of the diode consumes a larger
area than the integrated circuit being sensed. Therefore, it is desirable to provide
a thermal sensor which is incorporated into the integrated circuit. In addition,
it is desirable to provide a thermal sensor that can provide feedback for an active
cooling system. Furthermore, it is desirable to control the temperature of an integrated
circuit without the use of a fan. The present invention provides an integrated
thermal sensor that detects a threshold temperature so that active cooling of the
integrated circuit is accomplished through system control.
SUMMARY OF THE INVENTION
A programmable thermal sensor is implemented in an integrated circuit. The programmable
thermal sensor monitors the temperature of the integrated circuit, and generates
an output to indicate that the temperature of the integrated circuit has attained
a predetermined threshold temperature. The programmable thermal sensor contains
a voltage reference, a programmable V
be, a current source, and a sense
amplifier or comparator. The current source generates a constant current to power
the voltage reference and the programmable V
be. With a constant current
source, the voltage reference generates a constant voltage over varying temperatures
and power supply voltages. In a preferred embodiment, the voltage reference is
generated with a silicon bandgap reference circuit. The constant voltage from the
voltage reference is one input to the sense amplifier. The programmable V
be
contains a sensing portion and a multiplier portion. In general, the programmable
V
be generates a voltage dependent upon the temperature of the integrated
circuit and the value of programmable inputs. The programmable inputs are supplied
to the multiplier portion to generate a multiplier value for use in the multiplier
portion. The voltage reference is compared with the voltage generated by the programmable
V
be in the sense amplifier. The sense amplifier generates a greater
than, less than, signal.
The programmable thermal sensor of the present invention is implemented in a
microprocessor. In addition to the programmable thermal sensor, the microprocessor
contains a processor unit, an internal register, microprogram and clock circuitry.
The processor unit incorporates the functionality of any microprocessor circuit.
The clock circuitry generates a system clock for operation of the microprocessor.
In general, the microprogram writes programmable input values to the internal register.
The programmable input values correspond to threshold temperatures. The programmable
thermal sensor reads the programmable input values, and generates an interrupt
when the temperature of the microprocessor reaches the threshold temperature. In
a first embodiment, the interrupt is input to the microprogram and the processor
unit. In response to an interrupt, the processor unit may take steps to cool the
temperature of the microprocessor, and the microprogram programs a new threshold
temperature. For example, the processor may turn on a fan or reduce the clock frequency.
The new threshold temperature is slightly higher than the current threshold temperature
so that the processor unit may further monitor the temperature of the microprocessor.
In a second embodiment of the present invention, the interrupt generated by the
programmable thermal sensor is input to external sensor logic. The external sensor
logic automatically controls the frequency of the microprocessor. If the temperature
of the microprocessor raises, then the clock frequency is decreased. Conversely,
if the temperature of the microprocessor drops, then the system clock frequency
is increased. In addition to a programmable thermal sensor, the microprocessor
contains a fail safe thermal sensor. The fail safe thermal sensor generates an
interrupt when detecting that the microprocessor reaches predetermined threshold
temperatures and subsequently halts operation of the system clock. The predetermined
threshold temperature is selected below a temperature that causes physical damage
to the device. The microprocessor of the present invention is implemented in a
computer system. Upon generation of an interrupt in the programmable thermal sensor,
a message containing thermal sensing information is generated and displayed to
a user of the computer system.
BRIEF DESCRIPTION OF THE DRAWINGS
The objects, features, and advantages of the present invention will be apparent
from the following detailed description of the preferred embodiment of the invention
with references to the following drawings.
FIG. 1 illustrates a block diagram of a programmable thermal sensor configured
in accordance with the present invention.
FIG. 2 illustrates a graph depicting the relationship between the base-emitter
voltage (V
be) of a bipolar transistor versus the temperature of the
supply voltage.
FIG. 3 illustrates a bandgap reference circuit configured in accordance with
the present invention.
FIG. 4 illustrates a programmable base to emitter voltage (V
be) circuit
configured in accordance with the present invention.
FIG. 5 illustrates a current source, including the bandgap reference circuit,
configured in accordance with the present invention.
FIG. 6 illustrates a sense amplifier for the thermal sensor configured in accordance
with the present invention.
FIG. 7 illustrates block diagram of a first embodiment of a microprocessor incorporating
a programmable thermal sensor configured in accordance with the present invention.
FIG. 8 illustrates a flow diagram for a method of controlling the programmable
thermal sensor configured in accordance with the present invention.
FIG. 9 illustrates a block diagram of a second embodiment of a microprocessor
incorporating a programmable thermal sensor configured in accordance with the present invention.
FIG. 10 illustrates a block diagram of a microprocessor incorporating a fail
safe thermal sensor configured in accordance with the present invention.
FIG. 11 illustrates a computer system incorporating a microprocessor comprising
thermal sensing configured in accordance with the present invention.
NOTION AND NOMENCLATURE
The detailed descriptions which follow are presented, in part, in terms of algorithms
and symbolic representations of operations within a computer system. These algorithmic
descriptions and representations are the means used by those skilled in the data
processing arts to most effectively convey the substance of their work to others
skilled in the art.
An algorithm is here, and generally, conceived to be a self-consistent sequence
of steps leading to a desired result. These steps are those requiring physical
manipulations of physical quantities. Usually, though not necessarily, these quantities
take the form of electrical or magnetic signals capable of being stored, transferred,
combined, compared, and otherwise manipulated. It proves convenient at times, principally
for reasons of common usage, to refer to these signals as bits, values, elements,
symbols, characters, terms, numbers, or the like. It should be borne in mind, however,
that all of these and similar terms are to be associated with the appropriate physical
quantities and are merely convenient labels applied to these quantities.
Further, the manipulations performed are often referred to in terms, such
as adding or comparing, which are commonly associated with mental operations performed
by a human operator. No such capability of a human operator is necessary, or desirable
in most cases, in any of the operations described herein which form part of the
present invention; the operations are machine operations. Useful machines for performing
the operations of the present invention include general purpose digital computers
or other similar devices. In all cases there should be borne in mind the distinction
between the method operations in operating a computer and the method of computation
itself. The present invention relates to method steps for operating a computer
in processing electrical or other (e.g., mechanical, chemical) physical signals
to generate other desired physical signals.
The present invention also relates to apparatus for performing these operations.
This apparatus may be specially constructed for the required purposes or it may
comprise a general purpose computer as selectively activated or reconfigured by
a computer program stored in the computer. The algorithms presented herein are
not inherently related to a particular computer or other apparatus. In particular,
various general purpose machines may be used with programs written in accordance
with the teachings herein, or it may prove more convenient to construct more specialized
apparatus to perform the required method steps. The required structure for a variety
of these machines will appear from the description given below. Machines which
may perform the functions of the present invention include those manufactured by
Intel Corporation, as well as other manufacturers of computer systems.
DETAILED DESCRIPTION
Methods and apparatus for thermal sensing in an integrated circuit are disclosed.
In the following description, for purposes of explanation, specific nomenclature
is set forth to provide a thorough understanding of the present invention. However,
it will be apparent to one skilled in the art that these specific details are not
required to practice the present invention. In other instances, well known circuits
and devices are shown in block diagram form to avoid obscuring the present invention unnecessarily.
Referring to FIG. 1, a block diagram of a programmable thermal sensor configured
in accordance with the present invention is illustrated. In general, a programmable
thermal sensor 100 monitors the temperature of an integrated circuit, and
generates an output to indicate that the temperature of the integrated circuit
has attained a predetermined threshold temperature. The programmable thermal sensor
100 contains a voltage reference 120, a programmable V
be
110, a current source 140, and a sense amplifier 160. The
current source 140 generates a constant current to power the voltage reference
120 and the programmable V
be 110. With a constant current
source, the voltage reference 120 generates a constant voltage over varying
temperatures and power supply voltages (Vcc). In a preferred embodiment, the voltage
reference is generated with a silicon bandgap reference circuit. The constant voltage
from the voltage reference 120 is input to the sense amplifier 160.
The programmable V
be 110 contains a sensing portion and a multiplier
portion. In general, the programmable V
be 110 generates a voltage
dependent upon the temperature of the integrated circuit and the value of programmable
inputs. The programmable inputs are supplied to the multiplier portion to generate
a multiplier value for use in the multiplier portion.
Referring to FIG. 2, a graph depicting the relationship between the base-emitter
voltage (V
be) of a bipolar transistor versus temperature is illustrated.
A characteristic curve 200 on the graph of FIG. 2 shows the linear characteristics
of the V
be voltage over a temperature range of 70 degrees Fahrenheit
(70° F.) to 140° F. In addition, the graph of FIG. 2 shows a relative
constant bandgap voltage curve 205 over the specified temperature range.
Although the bandgap voltage varies slightly over the temperature range, the variation
of the bandgap voltage is negligible compared to the variation of the V
be
voltage over the temperature range. As shown by the curve 205 in FIG.
2, the bandgap voltage is equal to approximately 1.3 volts (V). When the V
be
voltage equals 1.3 volts, the temperature of the integrated circuit is 100°
F. Based on the linear temperature characteristics of the V
be voltage,
and the relatively constant bandgap voltage over the temperature range, a thermal
sensor is constructed.
For the voltage/temperature characteristics of line 200 shown in FIG.
2, the bandgap voltage equals the V
be voltage when the integrated circuit
is at 100° F. However, the V
be voltage may be changed to sense
additional temperature values in the integrated circuit. By shifting the linear
V
be voltage/temperature characteristic curve 200, any number
of predetermined threshold temperature values are detected. To shift the voltage/temperature
characteristic curve 200, the V
be voltage is multiplied
