# Help with transistor datasheet

1. Aug 14, 2016

On this datasheet￼ of PN2222A bipolar transistor

it is said that Vcesat at Ic/Ib=10 is about 0,3volts. However in the Icollector vs Vcesat graph for the same transistor that I will be posting immediately after I post this thread cause I cant add one more image here, it is shown that Vce hardly even exceeds 0,2 volts at 500mAmps. And im confused, what should I look at to find what value of Vcesat to expect at given collector current?

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2. Aug 14, 2016

And here's the graph

3. Aug 14, 2016

### Jony130

4. Aug 14, 2016

Hmm, so if we look at this datasheet, the developers have tested the transistor under 150mA Ic and under 500mA Ic and have gotten 0,3volts Vcesat for 150mA and 1volt for 500mA. And how do you engineers do in such a case? Do you choose a value let's say close to Ic= 150mA and Ib=15mA and expect a Vcesat of about 0,3volts? I want to learn what to do in such cases, how to know roughly what Vcesat I will get at a given current.

5. Aug 14, 2016

### Jony130

No single answer exist, It depends on an given application. Normally I assume that the Vce(sat) is around 0.2V for Ic<100mA and Ib = Ic/10 without even looking into data sheet. But for example if you build a single circuit just for hobby peruse you can use a typical value from figure 11. But if you want to design a circuit for a "spacecraft" then you must use a maximum value in your capitulations. For exampel you can assume Vce(sat) = 0.3V for Ic<150mA and Vce(sat) around 1V for Ic > 200mA.

6. Aug 14, 2016

:D thanks, that helped a lot!

7. Aug 14, 2016

### rbelli1

It's just one transistor. Not a whole robot army! ?

BoB