BJT Maximum Junction Voltages, VCEO, VCBO, VEBO


Transistor

On the datasheet for a BJT, there are normally 3 maximum junction voltages specifications that are given: VCEO, VCBO, and VEBO.

In this article, we will explain what the these ratings for VCEO, VCBO, and VEBO are and why they have value for circuit designers using these transistors.


Maximum Junction Voltages

VCEO
VCBO
VEBO


VCEO

The VCEO Rating of a Transistor is the maximum allowable voltage that the collector-emitter junction of a transistor can handle before it becomes damaged or destroyed.

The maximum allowable voltage that a junction of a transistor can withstand is called the breakdown voltage rating.

The VCEO rating which you see in a transistor datasheet is the breakdown voltage rating for the collector-emitter junction of the transistor.

Applying a voltage to the collector-emitter junction exceeding this rating can destroy the transistor. So make sure to check the datasheet for the transistor in use and design the circuit so that it receives a voltage lower than this rating across the collector-emitter junction.

VCBO

The VCBO Rating of a Transistor is the maximum allowable voltage that the collector-base junction of a transistor can handle before it becomes damaged or destroyed.

The VCBO rating which you see in a transistor datasheet is the breakdown voltage rating for the collector-base junction of the transistor.

Apply a voltage greater the VCBO rating across the collector-base junction can destroy the transistor. Again, make sure to look up this rating for the transistor in use to make sure this voltage isn't exceeded.

VEBO

The VEBO Rating of a Transistor is the maximum allowable voltage that the emitter-base junction of a transistor can handle before it becomes damaged or destroyed.

The VEBO rating which you see in a transistor datasheet is the breakdown voltage rating for the emitter-base junction of the transistor.

Again, this voltage must be checked on the transistor's datasheet to make sure it is not exceeded. Applying more voltage across the emitter-base junction than the VEBO rating can destroy the transistor, so design engineers normally make sure to check this rating and be within bounds of it.

As you can see explained above, each of these 3 voltages specifies the maximum voltage that a transistor can withstand for each respective junction without being destroyed. These values are important when doing circuit design to make sure that none of these junctions receive more voltage than their specified ratings. If so, the transistor can be destroyed and cause widespread damages to other parts of the circuit. Therefore, these ratings for a BJT are useful for these purposes.



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