Bjt npn base collector junction breakdown

In summary, when the NPN is in the forward active mode, the base emitter junction is forward biased and the base collector junction is reverse biased. It is possible for the base collector junction to break down if the CB bias voltage is increased, but it is usually biased below breakdown. There are various water analogies that can help explain BJTs, such as the one with pools of water and the base acting as a catalyst to start the water moving. However, some analogies may not accurately represent which junctions are reversed and forward biased.
  • #1
SpartanG345
70
1
When the NPN is in the forward active mode

The base emitter junction is forward biased and the base collector junction is reverse biased.
But isn't it possible for the base collector junction to break down? Or do we assume it never breaks down?

Also does anyone know any good water analogies that explain BJT's? I found some using google but they seem complicated.

I found this site http://www.satcure-focus.com/tutor/page4.htm
the 1st analogy doesn't seem to work that well when you think about which junctions are reversed and forward biased, but the second analogy seem ok - the one with the pools of water and the base acting as a catalyst to start the water moving

 
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  • #2
its possible that CB junction breaks down if u increase CB bias voltage . . .
usually collector base junction ll be biased below breakdown
 
  • #3
SpartanG345 said:
When the NPN is in the forward active mode

The base emitter junction is forward biased and the base collector junction is reverse biased.
But isn't it possible for the base collector junction to break down? Or do we assume it never breaks down?

Also does anyone know any good water analogies that explain BJT's? I found some using google but they seem complicated.

I found this site http://www.satcure-focus.com/tutor/page4.htm
the 1st analogy doesn't seem to work that well when you think about which junctions are reversed and forward biased, but the second analogy seem ok - the one with the pools of water and the base acting as a catalyst to start the water moving

Yes. Vceo is actually Vbc junction breakdown plus a diode drop with Vbe.
 

1. What is BJT NPN base collector junction breakdown?

BJT NPN base collector junction breakdown refers to the failure of the NPN transistor's base collector junction due to excessive voltage or current, resulting in a breakdown of the transistor and rendering it unusable.

2. What causes BJT NPN base collector junction breakdown?

BJT NPN base collector junction breakdown is typically caused by exceeding the maximum voltage or current ratings of the transistor, which can be due to overloading or improper circuit design.

3. How can I prevent BJT NPN base collector junction breakdown?

To prevent BJT NPN base collector junction breakdown, it is important to ensure that the transistor is not operated beyond its maximum voltage and current ratings. This can be done by carefully designing the circuit and using appropriate components.

4. What are the consequences of BJT NPN base collector junction breakdown?

The consequences of BJT NPN base collector junction breakdown can vary, but commonly include the failure of the transistor and potential damage to other components in the circuit. It can also lead to malfunctions or complete failure of the device or system in which the transistor is used.

5. Can BJT NPN base collector junction breakdown be repaired?

In most cases, BJT NPN base collector junction breakdown cannot be repaired. Once the junction has failed, the transistor is no longer functional and will need to be replaced. However, steps can be taken to prevent breakdown in the future through proper circuit design and component selection.

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