Why does the Darlington configuration work the way it does?

[iScience]

I know the Darlington configuration is supposed to sky rocket the beta value of the system, but this is only assuming the pair can handle that current right? It's a silly question but I just wanted to confirm...

I have two low current capacity transistors (I_max= 0.2A). so the setup can only handle a max of... 0.4A?

edit:

Is the configuration able to draw and handle more current than the combined Imax or does it just give u a high beta value?

 

[davenn]

hi there

the current gain of a Darlington pair is the sum of the gain (beta) of each transistor multiplied together
the advantage of this is that very small currents, like that from output pins of a microcontroller ( processor) can be used to switch high current loads
eg a Darlington pair with a current gain (Beta) of 1000 means that 1A could be switched with as little as 1mA.

I have two low current capacity transistors (I_max= 0.2A). so the setup can only handle a max of... 0.4A?

No, read on :)

Is the configuration able to draw and handle more current than the combined Imax or does it just give u a high beta value?

The current switching capability is still limited by the main ( output) transistor of the pair. This is because the driver transistor ( the first one) isn't passing any large current via its collector and emitter and into the base of the main transistorDave