Darlingtons vs. MOSFETs?

[mneary]

For saturation of a typical BJT (e.g. 2N2222) with a 400mA load, it really should have 40mA to its base. If you look carefully, you can find transistors with saturated beta as much as 50.

220 gives about 16mA; 470 gives only 7.5mA. (5V supply, 4.5V output, 1.0V saturated Vbe.)

Definitely should have a gate resistor on the MOSFET. Derating is good, too.

I agree, 250 is a better rule of thumb for the saturated beta of a Darlington. TIP121 for example is about 250, and ULN2003 is 400 or more.

 

[Styx]

meh, prefer closed-loop controls thus if output lower then it should be, the driver pushes harder. Don't need to worry abt things like that then (you other things )