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In the switching characteristics section of a BJT datasheet I often see test conditions like \$I_{B1}=I_{B2}=1mA\$. I understand this is the base current, but what exactly do they mean by \$I_{B1}\$ and \$I_{B2}\$?

Example: https://www.mccsemi.com/pdf/Products/MMBT3904(SOT-23).pdf

Velvel
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Jaywalk
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1 Answers1

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It means that the current for charging the Base is the same as the current used to discharge the Base capacitance when they do fall time testing. An exemplary circuit to do so is shown in this datasheet. enter image description here

You may also have a look at:

How to determine BJT switching time

Daniel K
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