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Derating Curve
In electronics, derating (or derating) is the operation of a device at less than its rated maximum capability to prolong its life. Typical examples include operations below the maximum power rating, current rating, or voltage rating. In electronics Power semiconductor devices have a maximum power dissipation rating usually quoted at a case temperature of . The datasheet for the device also includes a ''derating curve'' which indicates how much a device will dissipate without getting damaged at any given case temperature, and this must be taken into account while designing a system. As can be seen from the derating curve image for a hypothetical bipolar junction transistor, the device (rated for 100 W at ) cannot be expected to dissipate anything more than about 40 W if the ambient temperature is such that the temperature at which the device's case will stabilize (after heat-sinking) is . This final case temperature is a function of the thermal resistance between the device's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electronic Device
The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons using electronic devices. Electronics uses active devices to control electron flow by amplification and rectification, which distinguishes it from classical electrical engineering, which only uses passive effects such as resistance, capacitance and inductance to control electric current flow. Electronics has hugely influenced the development of modern society. The central driving force behind the entire electronics industry is the semiconductor industry sector, which has annual sales of over $481 billion as of 2018. The largest industry sector is e-commerce, which generated over $29 trillion in 2017. History and development Electronics has hugely influenced the development of modern society. The identification of the electron in 1897, along with the subsequent invention of the vacuum tube which could amplify and rectify small el ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Derating Curve
In electronics, derating (or derating) is the operation of a device at less than its rated maximum capability to prolong its life. Typical examples include operations below the maximum power rating, current rating, or voltage rating. In electronics Power semiconductor devices have a maximum power dissipation rating usually quoted at a case temperature of . The datasheet for the device also includes a ''derating curve'' which indicates how much a device will dissipate without getting damaged at any given case temperature, and this must be taken into account while designing a system. As can be seen from the derating curve image for a hypothetical bipolar junction transistor, the device (rated for 100 W at ) cannot be expected to dissipate anything more than about 40 W if the ambient temperature is such that the temperature at which the device's case will stabilize (after heat-sinking) is . This final case temperature is a function of the thermal resistance between the device's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bipolar Junction Transistor
A bipolar junction transistor (BJT) is a type of transistor that uses both electrons and electron holes as charge carriers. In contrast, a unipolar transistor, such as a field-effect transistor, uses only one kind of charge carrier. A bipolar transistor allows a small current injected at one of its terminals to control a much larger current flowing between the terminals, making the device capable of amplification or switching. BJTs use two p–n junctions between two semiconductor types, n-type and p-type, which are regions in a single crystal of material. The junctions can be made in several different ways, such as changing the doping of the semiconductor material as it is grown, by depositing metal pellets to form alloy junctions, or by such methods as diffusion of n-type and p-type doping substances into the crystal. The superior predictability and performance of junction transistors quickly displaced the original point-contact transistor. Diffused transistors, along wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heat Sink
A heat sink (also commonly spelled heatsink) is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant, where it is dissipated away from the device, thereby allowing regulation of the device's temperature. In computers, heat sinks are used to cool CPUs, GPUs, and some chipsets and RAM modules. Heat sinks are used with high-power semiconductor devices such as power transistors and optoelectronics such as lasers and light-emitting diodes (LEDs), where the heat dissipation ability of the component itself is insufficient to moderate its temperature. A heat sink is designed to maximize its surface area in contact with the cooling medium surrounding it, such as the air. Air velocity, choice of material, protrusion design and surface treatment are factors that affect the performance of a heat sink. Heat sink attachment methods and thermal interface materials also affect the die temperature of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal Resistance In Electronics
Thermal resistance is a heat property and a measurement of a temperature difference by which an object or material resists a heat flow. Thermal resistance is the reciprocal of thermal conductance. * (Absolute) thermal resistance ''R'' in kelvins per watt (K/W) is a property of a particular component. For example, a characteristic of a heat sink. * Specific thermal resistance or thermal resistivity ''Rλ'' in kelvin–metres per watt (K⋅m/W), is a material constant. * Thermal insulance has the units square metre kelvin per watt (m2⋅K/W) in SI units or square foot degree Fahrenheit–hours per British thermal unit (ft2⋅°F⋅h/Btu) in imperial units. It is the thermal resistance of unit area of a material. In terms of insulation, it is measured by the R-value. Absolute thermal resistance Absolute thermal resistance is the temperature difference across a structure when a unit of heat energy flows through it in unit time. It is the reciprocal of thermal conductance. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimmer
A dimmer is a device connected to a light fixture and used to lower the brightness of the lighting, light. By changing the voltage waveform applied to the lamp, it is possible to lower the luminous intensity, intensity of the light output. Although variable-voltage devices are used for various purposes, the term ''dimmer'' is generally reserved for those intended to lighting control system, control light output from resistive incandescent light, incandescent, halogen lamp, halogen, and (more recently) compact fluorescent lamps (CFLs) and light-emitting diodes (LED lamp, LEDs). More specialized equipment is needed to dim fluorescent lamp, fluorescent, mercury-vapor lamp, mercury-vapor, solid-state lighting, solid-state, and other arc lamp, arc lighting. Dimmers range in size from small units the size of domestic light switches to high-power units used in large theatrical or architectural lighting design, architectural lighting installations. Small domestic dimmers are generally ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heat Sink
A heat sink (also commonly spelled heatsink) is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant, where it is dissipated away from the device, thereby allowing regulation of the device's temperature. In computers, heat sinks are used to cool CPUs, GPUs, and some chipsets and RAM modules. Heat sinks are used with high-power semiconductor devices such as power transistors and optoelectronics such as lasers and light-emitting diodes (LEDs), where the heat dissipation ability of the component itself is insufficient to moderate its temperature. A heat sink is designed to maximize its surface area in contact with the cooling medium surrounding it, such as the air. Air velocity, choice of material, protrusion design and surface treatment are factors that affect the performance of a heat sink. Heat sink attachment methods and thermal interface materials also affect the die temperature of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Safe Operating Area
For power semiconductor devices (such as BJT, MOSFET, thyristor or IGBT), the safe operating area (SOA) is defined as the voltage and current conditions over which the device can be expected to operate without self-damage. SOA is usually presented in transistor datasheets as a graph with VCE (collector-emitter voltage) on the abscissa and ICE (collector-emitter current) on the ordinate; the safe 'area' referring to the area under the curve. The SOA specification combines the various limitations of the device — maximum voltage, current, power, junction temperature, secondary breakdown — into one curve, allowing simplified design of protection circuitry. Often, in addition to the continuous rating, separate SOA curves are also plotted for short duration pulse conditions (1 ms pulse, 10 ms pulse, etc.). The safe operating area curve is a graphical representation of the power handling capability of the device under various conditions. The SOA curve takes into account the wire bon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Underclocking
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, lifespan/reliability and compatibility. Underclocking may be implemented by the factory, but many computers and components may be underclocked by the end user. Types CPU underclocking For microprocessors, the purpose is generally to decrease the need for heat dissipation devices or decrease the electrical power consumption. This can provide increased system stability in high-heat environments, or can allow a system to run with a lower airflow (and therefore quieter) cooling fan or without one at all. For example, a Pentium 4 processor normally clocked at 3.4 GHz can be "underclocked" to 2 GHz and can then be safely run with reduced fan speeds. This invariably c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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