How can i know the current gain of transistor fom its data sheet?

In summary, when looking at a transistor's datasheet, it is important to note that Hfe values will vary between transistors and also as a function of temperature, collector current, and Vce. The given Hfe value at a specific Vce, such as 4 volts, will remain relatively constant within a certain range of Vce values. The plotted DC current gain on the datasheet is typically at a Vce that maximizes current gain.
  • #1
tefavolc
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how can i know the current gain of transistor fom its data sheet??

when i open a datasheet for a certain transistor i find a relation between Ic and Hfe at a certain Vce (ex Vce=4 volt), did this relation only correct at that Vce ? and if its that how can i calculate the Hfe for a certain Ic at any other value of Vce ? ?
i attach a data sheet for example
 

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  • #2


First you should know that Hfe will vary from one transistor to the next, even if it's the same type (eg tip31A), that's why the datasheet lists "typical' values.

Additionally, for any given transistor, Hfe will also vary as a function of temperature, as a function of collector current, and as a function of Vce.

The variation of Ic/Ib with collector voltage is large as you approach saturation but not so large for bigger values of Vce.

So to answer to your question, the value of Hfe given at Vce=4 volts will remain approximately constant for a range of Vce values, provided Vce stays greater than about a volt more than Vce_sat (and of course less than the Vce breakdown voltage).
 
  • #3


Note that the DC current gain plotted in Fig.1 of your transistor is plotted at a Vce that maximizes current gain.

Bob S
 
  • #4


thnx for replaying
 

1. How do I find the current gain of a transistor from its data sheet?

The current gain of a transistor can be found in the specifications section of its data sheet. It is usually denoted as hFE or β and is typically listed as a range of values for different operating conditions.

2. What does the current gain of a transistor indicate?

The current gain of a transistor indicates the amplification capabilities of the device. It is a measure of how much the output current will increase relative to the input current.

3. How do I interpret the current gain values listed on a transistor's data sheet?

The current gain values listed on a transistor's data sheet are typically given as a range of values. This is because the current gain can vary depending on factors such as temperature, biasing, and frequency. It is important to choose a transistor with a current gain that meets the requirements of your specific circuit.

4. Is the current gain of a transistor constant?

No, the current gain of a transistor is not constant. It can vary depending on various factors such as temperature, biasing, and frequency. It is important to consider these factors when selecting a transistor for a specific circuit.

5. Can I calculate the current gain of a transistor using its data sheet?

Yes, you can calculate the current gain of a transistor using the values listed on its data sheet. However, it may not be an accurate representation of the actual current gain in a circuit due to the varying factors mentioned previously. It is best to use the listed values as a guide and to test the transistor in your specific circuit to determine its actual current gain.

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