The typical values of ICBO at 25°C (the figures most often used for normal temperature) for small signal transistors are: Silicon: 0.01 µA to 1µA Germanium: 2 to 15 µA. The variation of ICBO with temperature is less in silicon as compared to germanium.
A silicontransistor is a semiconductor made with a silicon base. It is used in a wide variety of electronic devices, such as televisions and phones, to alter the flow of electrical current. Silicon has largely replaced germanium in transistors because of its ability to continue operating at high temperatures. The silicon transistor has other advantages over alternative materials, such as production cost, and thus is mass-produced in industrialized countries today.
A transistor is a device with an intermediate or variable electrical conductivity. It is used to amplify and divert electrical currents in electronic devices. This is typically done with a separate input signal that controls the flow of electricity through the transistor. The input signal can be changed by varying its voltage. Many transistors bundled together form an integrated circuit.
Texas Instruments, an American company, was the first to produce a silicon transistor in 1954. Before this, transistors were made of the element germanium. Germanium transistors worked fine at low temperatures, but had trouble at higher ones. If the transistors heated up, too many electrons would be freed from the germanium atoms. This was a major problem, because transistors only work with a limited number of electrons moving around.
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The derating factor of a transistor is the amount by which the power dissipation rating of a transistor falls when the transistor junction temperature increases.
The power dissipation rating of a transistor is usually given at 25°C. At higher temperatures, the power dissipation rating is less. For most silicon transistors, the maximum allowable junction temperature is between 150° and 200°C. Temperatureshigher than this will destroy the transistor. This is why a manufacturer must specify a maximum power rating for the transistor.
The transistor's power dissipation rating must be kept to less than its rated value so that the junction temperaturewill not reach destructive levels. Manufacturers usually supply derating factors for determining the power dissipation rating at any temperature above 25°C. The derating factor is specified in W/°C. For example, if a transistors has a derating factor of 2mW/°C, then for each1°C rise in junction temperature, the power rating of the transistor is reduced by 2mW.
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