In the switching characteristics section of a BJT datasheet I often see test conditions like "Ib1=Ib2=1mA". I understand this is base current but what exactly do they mean by Ib1 and Ib2? Example: https://www.mccsemi.com/pdf/Products/MMBT3904(SOT-23).pdf

Thanks in advanced.


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

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  • \$\begingroup\$ Thank you very much. Perfect answer in no time at all. \$\endgroup\$ – Jaywalk Jul 2 '19 at 13:26
  • \$\begingroup\$ You're welcome! Please accept my answer. \$\endgroup\$ – Daniel K Jul 2 '19 at 13:38

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