Showing papers on "Junction temperature published in 1988"

On-line monitoring of the mosfet device junction temperature by computation of the threshold voltage

Abstract: A method for an on-line junction temperature measurement is introduced. The circuit allows the calibration of a real-time thermal model of a power MOSFET. A regular calibration of the real-time model provides an accurate thermal flux model over the lifetime of the power MOSFET. The measurement of threshold voltage is used to determine the device temperature. The paper presents the on-line measurement method, the circuit and test results.

Microprocessor having high current drive and feedback for temperature control

Abstract: An integrated circuit having a microprocessor core interfaced to large power transistors is described. This integrated circuit provides the capability to intelligently control and drive loads requiring currents exceeding 250 milli amps. The large power transistors are built in a technology compatible with the microprocessor core technology resulting in a more readily manufacturable circuit. The microprocessor core is layed out in a manner which provides the greatest distance between the most heat sensitive microprocessor core circuits and the power devices. On chip temperature sensing and feedback is provided for junction temperature monitoring and control.

Microprocessor having high current drive

Abstract: An integrated circuit having a microprocessor core interfaced to large power transistors is described. This integrated circuit provides the capability to intelligently control and drive loads requiring currents exceeding 250 milli amps. The large power transistors are built in a technology compatible with the microprocessor core technology resulting in a more readily manufacturable circuit. The microprocessor core is layed out in a manner which provides the greatest distance between the most heat sensitive microprocessor core circuits and the power devices. On chip temperature sensing and feedback is provided for junction temperature monitoring and control.

Temperature control of light-emitting devices

Abstract: The temperature of the junction of a light-emitting semiconductor junction device 1 (e.g. an LED or laser diode) is measured by using the forward bias voltage/current characteristic of the device to provide an indication of the junction temperature and then controlling the temperature of the junction to a predetermined value in order to stabilise the output wavelength of the device. As shown the forward bias current of the device is measured by ammeter 3 and the forward voltage is measured by voltmeter 4. A signal processor 5 calculates the junction temperature and controls a temperature controller 6 to heat or cool the device. Alternatively the signal processor 5 may control the current source 2 and thereby vary the temperature of the junction by direct heating.

Factors affecting semiconductor device thermal resistance measurements

Abstract: The usual industry practice is to assume that thermal resistance of a semiconductor device is constant, and thus independent of power dissipation level or ambient environment temperature. In fact, thermal resistance is not a constant and varies with both power and temperature. The degree of variation is dependent on several factors: the range of power and temperature variation, the type of device, chip layout, mounting methods, etc. Rather than attempting to cover all aspects of the topic in overview fashion, only power dissipation and environmental temperature considerations are considered. Power dissipation considerations for a diode, a transistor, and an integrated circuit are described, to show that there are significant power-dissipation-induced variations of thermal resistance. Ambient environment temperature considerations are discussed to demonstrate that thermal resistance is also dependent on the environmental temperature to which a device is subjected during thermal testing. >

Low switching loss, high power gate turn-off thyristors (GTOs) with n-buffer and new anode short structure

Abstract: 6000-V gate-turn-off thyristors (GTOs) were developed for high-voltage power converters. In order to attain a high blocking voltages simultaneously with low turn-on and turn-off switching losses, a combination of an n-buffer layer and a cylindrical-anode short structure was implemented. This structure is effective in sweeping away excess carriers during turn-off transient without increasing the on-state voltage. The device, fabricated on a 33 mm diameter wafer, can turn off an anode current greater than 700 A at a junction temperature of 125 degrees C. >

A thermal analogue of higher accuracy and factory test method for predicting and supporting thyristor fault suppression ratings

Abstract: Because sophisticated computer modeling is not easily accessible, a one-dimensional thermal analogue is often used for routine calculations of virtual junction temperature occurring in thyristors when subjected to fault currents. The limitations of this procedure were found while establishing and improving fault suppression ratings of high-voltage (5 kV) thyristors. The thermal model was upgraded to include a number of heat sources within the silicon and some degree of two-dimensional heat spreading, while retaining the relative simplicity of a one-dimensional model. This upgraded model distinguishes the thermal impedance of the cathode junction from the thermal impedance of the anode junction. The supporting bench test was set up to use the calibrated off-state V/sub B0/ characteristic rather than the calibrated on-state drop of the signal current. It was found to be a more discriminating thermometer, responding to any existing hot spot temperature caused by surge current levels. Using certified thyristors, improved fault suppression ratings were established and subsequently proved under real power system conditions. >

Cold junction compensation apparatus

Abstract: A cold junction compensation apparatus utilizes a block of thermally conductive material, such as copper, having a mounting flange extending radially outwardly which is attached to a terminal strip by a machine screw to maintain the screw temperature substantially at the temperature of the block of thermally conductive material. The temperature of the block is sensed by means of a temperature sensor inserted into a hole extending through the block. The sensor is supported on a printed circuit board and is inserted through the hole in the block during assembly of an apparatus using the cold junction temperature compensation. The block is covered by an exterior insulating sleeve to prevent electrical shorts and rapid temperature changes in the block.

Microprocessor layout minimizing temperature and current effects

Abstract: An integrated circuit having a microprocessor core interfaced to large power transistors is described This integrated circuit provides the capability to intelligently control and drive loads requiring currents exceeding 250 milli amps The large power transistors are built in a technology compatible with the microprocessor core technology resulting in a more readily manufacturable circuit The microprocessor core is layed out in a manner which provides the greatest distance between the most heat sensitive microprocessor core circuits and the power devices On chip temperature sensing and feedback is provided for junction temperature monitoring and control

Reliability Prediction Models for Discrete Semiconductor Devices

Abstract: : The objective of this study was to update and revise the failure rate prediction models for discrete semiconductor devices currently in Section 5.1.3 of Mil-Hdbk-217e, Reliability Prediction of Electronic Equipment. GaAs Power FETS, Transient Suppressor Diodes, Infrared LEDs, Diode Array Displays and Current Regulator Devices. The proposed prediction models provide the ability to predict total device failure rate (both catastrophic and drift) for all military environments for both operating and non-operating modes. The updated models are formatted to be compatible with MIL-HDBK-217E and are included as an appendix to the Final Technical Report. Significant factors found to influence failure rate were device construction, semiconductor material, junction temperature, electrical stress, circuit application, application environment, package type and screen class. Keywords include: Reliability, Failure rate, MIL-HDBK-217, Discrete semiconductor, Diode, Transistor, Thyristor, Opto-electronic, and Microwave transistor.

An inverse method to determine the temperature profile on a semiconductor power diode

Abstract: An approach is developed to determine the nonuniform temperature profile on a semiconductor power diode. The temperature distribution over the large junction area of power semiconductor devices is often nonuniform due to voids or cracks in the mountdown media. Since the device packaging typically prevents direct measurement of the junction temperature, the presented technique requires the measurement of voltages and currents only. No information regarding the size or type of the void is required, and heat transfer equations are not solved. Instead, the temperature distribution is calculated using current-voltage-temperature relationships similar in form to the Shockley equation. Using these relationships, the temperature across the junction are calculated as a best fit to the voltage and current measurements. This inverse method is tested using a power diode 18 mm in diameter and rated at 100 A. Preliminary measurements indicate that the method calculates peak junction temperature as accurately as existing techniques. >

Low temperature measurements of UBe13

Abstract: Transport and specific heat measurements are reported on a new sample of UBe13. Special focuses are given on the zero field specific heat : at low temperature (T< 150mK) where the impurity scattering dominates, at intermediate temperature where a quasi T3 law characteristic of an axial state is obeyed and near the critical temperature where critical fluctuations are observed. Correlations are made with magnetoresistivity and thermal conductivity experiments.

Bibliography Of The Application Of Infrared Thermography To Electronic And Microelectronic Circuits

Abstract: Monitoring and Analyzing the Dynamic Junction Temperature Distribution of RF Power Transistors by Using RM-50 Infrared Micro-Imager

Overheat protection circuit

Abstract: PURPOSE:To make the setting of an operation temperature easy, and make the dispersion width of set temperature narrow, by a method wherein a constant current circuit is always normally operated by making a PNP transistor absorb the excess current of the constant current circuit before reaching an operation set temperature, and making it flow into a by-pass CONSTITUTION:A temperature detection circuit comprises transistors Q5, Q6 and Q10, and resistors R5-R7, and drives transistors Q7 and Q8 which constitute a control circuit Until P-N junction temperature reaches the operation set temperature of an overheat protection circuit the emitter current of the PNP transistor Q10 is a residual which results from ion of deduction of the collector current of the PNP transistor Q6 from that of PNP transistor Q5 At the operation time of overheat protection circuit, that is, the time when the PNP transistor Q7 operates, the emitter current of the transistor Q7 is supplied from the current flowing through the PNP transistor Q10, and the PNP transistor Q5 is not saturated Accordingly, the constant current circuit normally operates all the time

Power amplifier device

Abstract: PURPOSE:To drive a metal semiconductor type field effect transistor FET within a range wherein junction temperature is allowed from the point of reliability by cutting off the drain bias voltage of a power amplifier in a housing when the housing temperature rises above reference temperature. CONSTITUTION:The housing temperature is detected 45 and when the housing temperature rises above the reference temperature, the drain bias of the power amplifier is cut off, so the FET 34 turns off to prevent the junction temperature of the FET 34 from rising above the permissive temperature of reliability. At this time, drain bias power supply and the power consumption of the FET 34 are nearly eliminated, so the housing temperature of the power amplifier falls and when it falls below the reference temperature, the FET 34 turns on again. Consequently, the power amplifier is put in operation while the junction temperature of the FET is held below the permissible temperature of reliability.

Thermal dissipation characteristics of a non-hermetic metal dual in-line package

Abstract: A study is described that evaluated the benefits of a metal cavity package on junction temperature and examined consequences of die-attach methods on a device's thermal properties. The measurements made to establish some of the factors affecting thermal transfer are outlined. Both infrared (IR) thermography and standard measurement methods were used to determine the thermal resistance for both a standard plastic dual-in-line package (P-DIP) and metal cavity package. The benefits of both approaches in assessing general thermal characteristics of the packages are discussed. The use of a metal cavity package was found to provide an excellent means of heat removal from the base of the die as long as die attach methods are sound, and the die attach medium is thermally conductive. It is also shown that it is possible to examine heat paths from the die to the case both qualitatively and quantitatively by IR thermography. >

Monitoring and analyzing the dynamic junction temperature distribution of RF power transistors by using RM-50 infrared micro imager

Abstract: The authors describe experiments carried out on three types of RF power transistors typically used in the power amplifiers of communication systems. Because of differences found when measuring junction temperatures, a dynamic heat resistance concept was formulated to describe the dynamic thermal characteristics of RF power transistors. Using this concept, the handling capability, burn-in testing, life testing, and the reliability design of RF power transistors were studied. Among the results presented, it was found that the dynamic peak heat resistance is generally lower than the steady peak heat resistance, and steady peak heat resistance is more sensitive than the dynamic peak heat resistance to increasing DC voltage. >

Influence Of LED Optical Characteristic Variations On Performance Of A Plastic Optical Fiber Transmission Link

Abstract: Influence of LED Optical Characteristic Variationson Performance of aPlastic Optical Fiber Transmission LinkE.Moschim, H.Ding, A.Destrez and G.AttalEcole Superieure d'Electricite, Service Radioelectricite et ElectroniquePlateau du Moulon, 91190, Gif sur Yvette, FranceAbstractPlastic optical fiber transmission link (POFTL) becomes an atractive option for short distance LAN's andindustrial applications. In this work, we investigate the influence of LED optical characteristic variationsdue to its junction temperature changements on performances of a PMMA core POFTL. A selective loss As isintroduced for this purpose. The value of As is found to be 0.330/km °C.IntroductionRecently plastic optical fiber transmission link (POFTL) becomes an atractive option for short distanceLAN's and industrial applications, because of its low installation and maintenance cost.] PMMA core plasticfiber, which is actually available on the market, has the following particular properties: its attenuationis 1) high and, 2) very sensitive to light wavelength. As a consequence, the maximal length of; POFTL withoutrepeater is limited to low values and all LED spectral variations will change POFTL performance to anonnegligible level.Our aim is to investigate this effect. We give out in section II some measured optical characteristicvariations of a LED at 660nm due to its junction temperature changements. This kind of LED is well adaptedfor the POFTL applications.2 In section III, a simple POFTL model is proposed. The influence of LED opticalcharacteristic variations on performances of POFTL is examined by introducing a selective loss As. Section IVis our conclusions.II. Optical characteristic variations of a LED at 660nm caused by junction temperature changementAny changement in the junction temperature of a LED will alter its principal optical characteristics: peakemission wavelength, spectrum, emission power and modulation linearity. Junction temperature changements maybe caused by ambient temperature variations or by LED's bias current variations. Several works have beendevoted to this subject.i Here we show only the measured results of a LED at 660nm, which are used in our

The design of a reduced ambient temperature, air cooled supercomputer

Abstract: The authors summarize the forces which drive the packaging design of a supercomputer. They focus on using controlled junction temperature cooling of CMOS VLSI as an approach to obtaining improved performance. A cursory review of heat transfer physics is given, borrowing ideas used in heat exchanger design from the process industry. Some specific examples are discussed: finite-element solutions to level-0 and -1 package conduction problems and experimental solutions to air-flow problems at both the heat sink and card/cage/system (levels 2, 3, and 4). It is noted that the very high level of integration possible using 1.0- mu m CMOS allows implementation of the entire logic of a supercomputer in a small number of chips, allowing more complex, parallel architectures with large shared memory to be developed. >