Linear regulator...use NPN , or NPN_Darlington?

[Flyback]

Hi,
Linear regulator 85V to 69.5V at 350W.
You are going to use parallel BJTs
Why would you ever use an NPN instead of a NPN_Darlington for this?

Eg why MJ15022 instead of the Darlington MJ11022?

MJ15022 (NPN)
https://www.mouser.co.uk/datasheet/2/308/1/MJ15022_D-2316114.pdf
MJ11022 (NPN Darlington)
https://www.onsemi.com/pdf/datasheet/mj11021-d.pdf

 

[rjenkinsgb]

A Darlington has a minimum drop in excess of 0.6V even when as near saturation as one ever can be, as the base of the second transistor is fed from its own collector.

A properly configured and driven single transistor can have much lower saturation voltage, and so lower power dissipation.

And, probably more relevant in that application - faster transient response as the base can be driven as fast as needed, both positive and negative, rather than relying on the internal base-emitter resistor in the Darlington.

That Darlington has a typical switch-off time of 10uS, from the data sheet.