Aplicaciones BJT
power transistors are finding increasing popularity in applications of low to medium power. A power transistor current gain is low and requires continuous base unit in the state in a position, but does not require forced feeding commutations.Circuitry transistors can be used in high frequency switching, which allows size reduction electromagnetic components and can provide a current limit protection for the transistor circuit.Power base unit can not support a reverse voltage and the application is limited to a DC voltage for investors and helicopters.
Sunday, July 25, 2010
Carolina Lab Cell Respiration
A transistor is a three layer pnp or npn semiconductor device HAVING junctions.This two type of transistors is know as bipolar junction transistor (BJT). The structure and symbol of npn transistor is Shown below.
A pnp transistor is a three layer semiconductor device with two junctions.This npn transistor type is known as the bipolar junction transistor (BJT). The structure and npn transistor symbol is shown below.
The three terminal device is called the collector (c), base (B) and emitter (E). The collector
ans Are Emitter terminals connected to the main power circuit, the base terminal is connected to control signal. Ans The collector emitter terminals are connected to main power circuit, the base terminal is connected to the control signal.
Can Be
Transistors operated in the switching mode. transistor is in an off state and Behaves as a switch.On the Other Hand, if the base is driven hard, ie if the base current I B 
is Sufficient to drive the transistor saturation Into, Then the transistor Behaves as a closed switch. If the base current I B
zero transistor is in a disconnected state and behaves as a switch.On On the other hand, if the base is excited too, ie if the base current
B it is sufficient to drive the transistor into saturation, the transistor behaves like a closed switch. The transistor is a current driven current base device.The Determines whether it is in on state or off state.To keep the device in on state, There Should Be a Sufficient base current. The transistor base current is a current driven device.The determines whether in state or out of state.To hold the device in the state, must be a sufficient base current.
Transistor with high voltage and current ratings Are Known as power transistors. The current gain of power transistors (I C / I 
B) Can Be as low as 10.For eg. Transistor high voltage and current are known as power transistors. The current gain power transistors (I
C B) Can Be as low as 10.For eg. Transistor high voltage and current are known as power transistors. The current gain power transistors (I / B I) can be as low as 10.For for example. base current of 10A is required for collector current of 100A. 10A current base 100 A is required for collector current.
Power transistors switch on and off much faster Than May thyristors.They switch on in Less Than 1μs and turnoff in Less Than 2μs.Therefore power transistors Applications Can Be Used in WHERE frequency is as high as 100kHz.These Are devices fail under Certain delicate.They very high voltage and high current operated conditions.They Should Be Specified STI Within limits, Known as Safe Operating area (50A). power transistors on and off much faster than you can change the thyristors.They in less than 1μs and diversion within 2μs.Therefore power transistors can be used in applications where the frequency is as high as devices delicate.They 100kHz.These are not on the high voltage and high current conditions.They some should be operated within specified limits, known as the safe operating area (50A). The output Characteristics of CE configuration is as Shown Below The output characteristics of CE configuration is as follows The
depict the relation entre características collector current (I C ) emitter and collector to voltage (V CE
) for Different values \u200b\u200bof current.These características base is of npn transistor.These características Have three regions ie active region, saturation region and cut off. characteristics describe the relationship between collector current (I C) and the collector to emitter voltage (V EC) for different values \u200b\u200bof characteristic features is based current.These transistor.These npn have three regions ie active region, saturation and cutoff region. The características input Depicts the Relationship Between base current I B
and emitter to base voltage for Different values \u200b\u200bof collector to emitter voltage V CE. input features representing the relationship between base current I B
and emitter to base voltage for different values \u200b\u200bof collector to emitter voltage V CE. 
características The input is Shown in the figure Below input features shown in the figure below The VI CHARACTERISTICS (Characteristics of output power transistor npn Below is Shown in figure VI characteristics (output characteristics of npn power transistor shown in the image
As in the case of lower power BJT, this características depict the Relationship Between collector current (I C ) emitter and collector to voltage (V CE ) for Different values \u200b\u200bof base current I B. As in the case of lower power BJT, these features represent the ratio between collector current (I C)
and the collector to emitter voltage (V EC) for different values \u200b\u200bof base current I B.
It is Seen That These Have Some special features características very Different from Those for lower power as FOLLOWS Are BJT.These features. is seen that these characteristics have some special characteristics very different from BJT.These lower power consumption characteristics are as follows.
1. 1. For substantial businesses 
values \u200b\u200bof collector current, There is maximum value of collector emitter voltage Which dog sustain the device, it is denoted as BVsus in Above figure.If
I 
values \u200b\u200bof collector current, There is maximum value of collector emitter voltage Which dog sustain the device, it is denoted as BVsus in Above figure.If B = 0 the maximum voltage Which Can Be Sustained by Increases to the device BV CEO . (The voltage (V CE ) When the base is open circuited). The voltage CBO BV is the breakdown voltage When the emitter is open circuited. For substantial values \u200b\u200bof the collector current, there is a maximum collector emitter voltage that the device can hold, as is noted in previous BVsus figure.If I B = 0, the maximum voltage that can be sustained by increases device BV CEO. ( Voltage (V AD) when the base is open circuit). The tension BV CBO is the breakdown voltage when the emitter is open circuit.
2. 2. The primary breakdown is due to the avalanche breakdown of CB junction.In this region the current and the power dissipation very high.Therefore Can Be Should Be Avoided this region. The main cast is due to avalanche breakdown by CB junction.In this region the current and power dissipation can be very high.Therefore this region should be avoided.
3. 3. Marked In the second breakdown region, Substantially Decrease The CE voltage and the collector current is high.This region is due to thermal runaway. A cumulative process Occurs in this region and the device gets destroyed.In this breakdown, power dissipation is Not uniformly spread over the volume of the transistor Entire But Rather is restricted to Highly localized areas.Therefore the chances of the device getting high Are Destroyed. In the region marked the second crisis, the voltage decreases substantially CE and the collector current is high.This region is due to thermal runaway. A cumulative process occurs in this region and the device is destroyed.In this breakdown, the energy dissipation is distributed evenly over the entire volume of the transistor, but is rather restricted to very localized areas.Therefore the chances that the device be destroyed are high. 4. 4. A quasi saturation (between saturation and active region) exists.This region is due to the region Lightly doped collector drift region. A quasi-saturation (between saturation and the active region) region exists.This region is due to drift lightly doped collector region. PREPARED BY: ANTONIO MORA NERWIN REINOSO CI: 17,557,095
EES SECTION 1
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