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

#### tefavolc

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

#### Attachments

• 527 KB Views: 206

#### uart

Re: how can i know the current gain of transistor fom its data sheet??

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).

#### Bob S

Re: how can i know the current gain of transistor fom its data sheet??

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

Bob S

#### tefavolc

Re: how can i know the current gain of transistor fom its data sheet??

thnx for replaying

### The Physics Forums Way

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving