Saturation and active zone

[julian403]

I know that the transistor has 3 areas of work. In the saturation zone Ic depends on the load. In the active zone Ic depende de Ib.

what determines whether a transistor is in saturation or active? I think that it's the current ib because Ic must be proportional to Ib, so given a Ib the Vce will be available to have, for a particular circuit, a voltage to drive Ic which it's proportional to ib. But I'm not sure because Ic saturation depends only on the load. So how do we establish in saturation?

greetings.

 

[barry]

By definition (for what it's worth) a transistor is considered to be in saturation when both the B-E and B-C junctions are forward biased.

 

[yassin.kraouch]

I know that the transistor has 3 areas of work. In the saturation zone Ic depends on the load. In the active zone Ic depende de Ib.

what determines whether a transistor is in saturation or active? I think that it's the current ib because Ic must be proportional to Ib, so given a Ib the Vce will be available to have, for a particular circuit, a voltage to drive Ic which it's proportional to ib. But I'm not sure because Ic saturation depends only on the load. So how do we establish in saturation?

greetings.

to determine if a transistor is in saturation or active, i will give you rule i used all time:
-If we have Ib different from 0 we can say that the transistor is not in cut off region.
-a transistor in saturation should have Vce>0.2V
-you have first to calculate Ib
-you have to suppose that the transistor is in active region, and based in this you can say that Ic=(beta)*Ib
-you know Vcc, than you can calculate Vce, if you find some negative values, or something that is not logic, so the transistor in not active, and is in saturation.
-if you find Vce > 0.2 than the transistor is in active region.

 

[Audioguru]

The maximum collector to emitter saturation voltage for a 2N3055 power transistor with a collector current of only 10A (its maximum collector current is 15A) and a base current of a whopping 3.3A is 3.0V which is MUCH more than 0.2V that was said.

Frequently a little 2N3904 transistor has a typical saturation voltage of 0.05V but its maximum is 0.3V.

 

[julian403]

thanks for all.