# Operating temperature

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An operating temperature is the temperature at which an electrical or mechanical device operates. The device will operate effectively within a specified temperature range which varies based on the device function and application context, and ranges from the minimum operating temperature to the maximum operating temperature (or peak operating temperature). Outside this range of safe operating temperatures the device may fail.

## Contents

It is one component of reliability engineering.

Similarly, biological systems have a viable temperature range, which might be referred to as an "operating temperature".

## Ranges

• Commercial: 0 ° to 70 °C
• Industrial: −40 ° to 85 °C
• Military: −55 ° to 125 °C

Nevertheless, each manufacturer defines its own temperature grades so designers must pay close attention to actual datasheet specifications. For example, Maxim Integrated uses five temperature grades for its products: [2]

• Full Military: −55 °C to 125 °C
• Automotive: −40 °C to 125 °C
• AEC-Q100 Level 2: −40 °C to 105 °C
• Extended Industrial: −40 °C to 85 °C
• Industrial: −20 °C to 85 °C

The use of such grades ensures that a device is suitable for its application, and will withstand the environmental conditions in which it is used. Normal operating temperature ranges are affected by several factors, such as the power dissipation of the device. [3] These factors are used to define a "threshold temperature" of a device, i.e. its maximum normal operating temperature, and a maximum operating temperature beyond which the device will no longer function. Between these two temperatures, the device will operate at a non-peak level. [4] For instance, a resistor may have a threshold temperature of 70 °C and a maximum temperature of 155 °C, between which it exhibits a thermal derating. [3]

For electrical devices, the operating temperature may be the junction temperature (TJ) of the semiconductor in the device. The junction temperature is affected by the ambient temperature, and for integrated circuits, is given by the equation: [5]

${\displaystyle T_{J}=T_{a}+P_{D}\times R_{ja}}$

in which TJ is the junction temperature in °C, Ta is the ambient temperature in °C, PD is the power dissipation of the integrated circuit in W, and Rja is the junction to ambient thermal resistance in °C/W.

## Aerospace and military

Electrical and mechanical devices used in military and aerospace applications may need to endure greater environmental variability, including temperature range.

In the United States Department of Defense has defined the United States Military Standard for all products used by the United States Armed Forces. A product's environmental design and test limits to the conditions that it will undergo throughout its service life are specified in MIL-STD-810, the Department of Defense Test Method Standard for Environmental Engineering Considerations and Laboratory Tests. [6]

The MIL-STD-810G standard specifies that the "operating temperature stabilization is attained when the temperature of the functioning part(s) of the test item considered to have the longest thermal lag is changing at a rate of no more than 2.0 °C (3.6 °F) per hour." [6] It also specifies procedures to assess the performance of materials to extreme temperature loads. [7]

Military engine turbine blades experience two significant deformation stresses during normal service, creep and thermal fatigue. [8] Creep life of a material is "highly dependent on operating temperature", [8] and creep analysis is thus an important part of design validation. Some of the effects of creep and thermal fatigue may be mitigated by integrating cooling systems into the device's design, reducing the peak temperature experienced by the metal. [8]

## Commercial and retail

Commercial and retail products are manufactured to less stringent requirements than those for military and aerospace applications. For example, microprocessors produced by Intel Corporation are manufactured to three grades: commercial, industrial and extended. [9]

Because some devices generate heat during operation, they may require thermal management to ensure they are within their specified operating temperature range; specifically, that they are operating at or below the maximum operating temperature of the device. [10] Cooling a microprocessor mounted in a typical commercial or retail configuration requires "a heatsink properly mounted to the processor, and effective airflow through the system chassis". [10] Systems are designed to protect the processor from unusual operating conditions, such as "higher than normal ambient air temperatures or failure of a system thermal management component (such as a system fan)", [10] though in "a properly designed system, this feature should never become active". [10] Cooling and other thermal management techniques may affect performance and noise level. [10] Noise mitigation strategies may be required in residential applications to ensure that the noise level does not become uncomfortable.

Battery service life and efficacy is affected by operating temperature. [11] Efficacy is determined by comparing the service life achieved by the battery as a percentage of its service life achieved at 20 °C versus temperature. Ohmic load and operating temperature often jointly determine a battery's discharge rate. [12] Moreover, if the expected operating temperature for a primary battery deviates from the typical 10 °C to 25 °C range, then operating temperature "will often have an influence on the type of battery selected for the application". [13] Energy reclamation from partially depleted lithium sulfur dioxide battery has been shown to improve when "appropriately increasing the battery operating temperature". [14]

## Biology

Mammals attempt to maintain a comfortable body temperature under various conditions by thermoregulation, part of mammalian homeostasis. The lowest normal temperature of a mammal, the basal body temperature, is achieved during sleep. In women, it is affected by ovulation, causing a biphasic pattern which may be used as a component of fertility awareness.

In humans, the hypothalamus regulates metabolism, and hence the basal metabolic rate. Amongst its functions is the regulation of body temperature. The core body temperature is also one of the classic phase markers for measuring the timing of an individual's Circadian rhythm. [15]

Changes to the normal human body temperature may result in discomfort. The most common such change is a fever, a temporary elevation of the body's thermoregulatory set-point, typically by about 1–2 °C (1.8–3.6 °F). Hyperthermia is an acute condition caused by the body absorbing more heat than it can dissipate, whereas hypothermia is a condition in which the body's core temperature drops below that required for normal metabolism, and which is caused by the body's inability to replenish the heat that is being lost to the environment. [16]

## Notes

1. Analog Devices, Power dissipation.
2. Vassighi & Sachdev 2006, p. 32.
3. United States Department of Defense, section 2.1.1.
4. Pentium Processor Packing Identification CodesIntel's packaging indicates the processors operating temperature range by denoting it with a grade: 'Q' (commercial grade), 'I' (industrial grade), and 'L' or 'T' (extended grade). It also has an automotive grade 'A'
5. Crompton 2000, p. figure 30.33.
6. Crompton 2000, p. 2/5, section 2.1.
7. Marx 2010, p. 1870.

## Related Research Articles

A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses. High-power resistors that can dissipate many watts of electrical power as heat, may be used as part of motor controls, in power distribution systems, or as test loads for generators. Fixed resistors have resistances that only change slightly with temperature, time or operating voltage. Variable resistors can be used to adjust circuit elements, or as sensing devices for heat, light, humidity, force, or chemical activity.

A thermistor is a type of resistor whose resistance is strongly dependent on temperature, more so than in standard resistors. The word is a combination of thermal and resistor. Thermistors are widely used as inrush current limiters, temperature sensors, self-resetting overcurrent protectors, and self-regulating heating elements.

Transistor–transistor logic (TTL) is a logic family built from bipolar junction transistors. Its name signifies that transistors perform both the logic function and the amplifying function, as opposed to resistor–transistor logic (RTL) or diode–transistor logic (DTL).

In computing, overclocking is the practice of increasing the clock rate of a computer to exceed that certified by the manufacturer. Commonly, operating voltage is also increased to maintain a component's operational stability at accelerated speeds. Semiconductor devices operated at higher frequencies and voltages increase power consumption and heat. An overclocked device may be unreliable or fail completely if the additional heat load is not removed or power delivery components cannot meet increased power demands. Many device warranties state that overclocking and/or over-specification voids any warranty, however there are an increasing number of manufacturers that will allow overclocking as long as performed (relatively) safely.

Processor power dissipation or processing unit power dissipation is the process in which computer processors consume electrical energy, and dissipate this energy in the form of heat due to the resistance in the electronic circuits.

Underclocking, also known as downclocking, is modifying a computer or electronic circuit's timing settings to run at a lower clock rate than is specified. Underclocking is used to reduce a computer's power consumption, increase battery life, reduce heat emission, and it may also increase the system's stability and compatibility. Underclocking may be implemented by the factory, but many computers and components may be underclocked by the end user.

A heat pipe is a heat-transfer device that combines the principles of both thermal conductivity and phase transition to effectively transfer heat between two solid interfaces.

In electrical engineering and mechanical engineering, the power rating of equipment is the highest power input allowed to flow through particular equipment. According to the particular discipline, the term "power" may refer to electrical or mechanical power. A power rating can also involve average and maximum power, which may vary depending on the kind of equipment and its application.

Computer cooling is required to remove the waste heat produced by computer components, to keep components within permissible operating temperature limits. Components that are susceptible to temporary malfunction or permanent failure if overheated include integrated circuits such as central processing units (CPUs), chipsets, graphics cards, and hard disk drives.

A voltage regulator module (VRM), sometimes called processor power module (PPM), is a buck converter that provides a microprocessor the appropriate supply voltage, converting +5 V or +12 V to a much lower voltage required by the CPU, allowing processors with different supply voltage to be mounted on the same motherboard. On personal computer (PC) systems, the VRM is typically made up of power MOSFET devices.

Ampacity is a portmanteau for ampere capacity defined by National Electrical Codes, in some North American countries. Ampacity is defined as the maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. Also described as current-carrying capacity.

Capacitors are manufactured in many forms, styles, lengths, girths, and from many materials. They all contain at least two electrical conductors separated by an insulating layer. Capacitors are widely used as parts of electrical circuits in many common electrical devices.

All electronic devices and circuitry generate excess heat and thus require thermal management to improve reliability and prevent premature failure. The amount of heat output is equal to the power input, if there are no other energy interactions. There are several techniques for cooling including various styles of heat sinks, thermoelectric coolers, forced air systems and fans, heat pipes, and others. In cases of extreme low environmental temperatures, it may actually be necessary to heat the electronic components to achieve satisfactory operation.

Junction temperature, short for transistor junction temperature, is the highest operating temperature of the actual semiconductor in an electronic device. In operation, it is higher than case temperature and the temperature of the part's exterior. The difference is equal to the amount of heat transferred from the junction to case multiplied by the junction-to-case thermal resistance.

Photovoltaic thermal collectors, typically abbreviated as PVT collectors and also known as hybrid solar collectors, photovoltaic thermal solar collectors, PV/T collectors or solar cogeneration systems, are power generation technologies that convert solar radiation into usable thermal and electrical energy. PVT collectors combine photovoltaic solar cells, which convert sunlight into electricity, with a solar thermal collector, which transfers the otherwise unused waste heat from the PV module to a heat transfer fluid. By combining electricity and heat generation within the same component, these technologies can reach a higher overall efficiency than solar photovoltaic (PV) or solar thermal (T) alone.

A tantalum electrolytic capacitor is an electrolytic capacitor, a passive component of electronic circuits. It consists of a pellet of porous tantalum metal as an anode, covered by an insulating oxide layer that forms the dielectric, surrounded by liquid or solid electrolyte as a cathode. Because of its very thin and relatively high permittivity dielectric layer, the tantalum capacitor distinguishes itself from other conventional and electrolytic capacitors in having high capacitance per volume and lower weight.

An environmental chamber, also called a climatic chamber or climate chamber, is an enclosure used to test the effects of specified environmental conditions on biological items, industrial products, materials, and electronic devices and components.

Panasonic Toughpad is a series of tablet computers developed and designed by Panasonic as a subset of its series of Toughbook rugged computers. The first Toughpad was unveiled on November 7, 2011 in the United States.

Film capacitors, plastic film capacitors, film dielectric capacitors, or polymer film capacitors, generically called "film caps" as well as power film capacitors, are electrical capacitors with an insulating plastic film as the dielectric, sometimes combined with paper as carrier of the electrodes.

AMD Turbo Core a.k.a. AMD Core Performance Boost (CPB) is a technology implemented by AMD that allows the processor to dynamically adjust and control the processor operating frequency in certain versions of its processors which allows for increased performance when needed while maintaining lower power and thermal parameters during normal operation. AMD Turbo Core technology has been implemented beginning with the Phenom II X6 microprocessors based on the AMD K10 microarchitecture. AMD Turbo Core is available with some AMD A-Series accelerated processing units.

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