Transistor Base, Emitter, Collector -Voltage Question

Discussion in 'Datasheets, Manuals and Component Identification' started by ag273n, Feb 3, 2017.

1. ag273n

74
4
Nov 24, 2016
just want to clarify if my understanding is correct..

An example Transistor 2N3904 has the below datasheet

1.) Is the VCEO the voltage that can go through from Collector to Emitter without damaging it?
2.) and so VEBO - would be the maximum voltage to like "Switch On" the transistor correct?..

2. OBW0549

157
117
Jul 5, 2016
Yes, Vceo is the maximum voltage that can be applied from collector to emitter.

No. That's the maximum reverse voltage that can be applied from base to emitter before the b-e junction breaks down. With zero or reverse b-e voltage, the transistor is off, not on.

3. ag273n

74
4
Nov 24, 2016
thanks...
does the Base have like a maximum voltage to "Turn on" the collector - emitter connection?
--- and does it limit the voltage going through depending on the voltage in the Base? - or is it like any amount of voltage on the base will completely turn on the Collector to emitter?

4. OBW0549

157
117
Jul 5, 2016
Any book on basic electronics will answer these questions for you. There is also a wealth of informative material online; just Google the phrase "how does a transistor work" and you'll get plenty of good information.

5. LvW

604
146
Apr 12, 2014
From the physical point of view - there is nothing like a "turn-on voltage" between base and emitter.
The relation between the collector current and the controlling base-emitter voltage Vbe is an exponenetial function (Shockley equation): Ic=Is*exp[(Vbe/Vt)-1] .
From this, you can see that there is a current Ic even for rather small voltages Vbe.

However, we have another situation if the transistor is used as a switch. In this case, we are considering only two distinct operational conditions: On (max. possible current) and Off (zero current).

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6. ag273n

74
4
Nov 24, 2016
Thanks LvW... i did some digging and found the below from a Dummies book

i simply wanted to put together a small chart with such info of the commonly used transistors on most schematics i find... this way i can understand why that transistor is in place, and replace it with a similar one in case i had to. At this point, i got what i need