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BJT is getting hot when it provide 160mA

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Lucifre

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I am using 2N2907 PNP transistor, it is rated to provide maximum current of 600 mA. I am using it in a circuit that provides 160mA and it is very hot when i touch it
I double checked all the connections and they appear to be correct
Is it normal for BJT to get that hot?
 

aryajur

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Re: BJT is getting hot

Normal operation at high currents does make BJTs and other transistors hot. Check the voltage across Emitter and Collector and then you will know the power it is dissipating. So from that you can determine if it needs a heatsink or not. Maybe the datasheet mentions a safe power dissipation level for the transistor.
 

echo47

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BJT is getting hot

Power dissipation causes the heat. Power is current times voltage.

The SGS Thomson 2N2907A data sheet specifies 600 mA maximum collector current, and 400 mW maximum power dissipation (assuming ambient temperature 25C). Both are important. Don't exceed the dissipation rating unless you use a heatsink and understand the transistor+heatsink thermal properties.
 

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Re: BJT is getting hot

Ok i know why it is gettig hot now.... when i multiply emitter current (little less than 161mA) with Vec(around 7 i get 1.12 W!!! he he he my fault i should use lower supply voltage that's all thanx a lot guys
 

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