Switching the high side using NPN and PNP

Projects General Guidance
1

I need to switch the high side of 16 devices. I think a transistor setup is the best due to size requirements but I'm not sure...

At the moment I'm thinking a NPN transistor driving a PNP would be my best bet.
Im thinking:

NPN: MMBT5551
PNP: BDW47

In this circuit:

with:

Resistor 1: 2.2k / 0.250w
Resistor 2: 680ohm / 0.250w
Resistor 3: 6.8kOhms / 0.250w
Resistor 4: 22kOhm / 0.250w

I'm very new to the theory side of selecting components such as resistors and diodes so have no idea if these are the correct resistors to use.

I would like to make it so I could reuse it with different voltages i.e have the outputs the same as the Vin.
I have a input side of things sorted.

I think I will have a problem with changing the supply voltage because of the resistor values.

Do you think I have selected the correct transistor setup? And what problems will I encounter if I change the supply voltage and how would I over come them?

Thanks in advance!

2

There is no point in selecting particular transistors and resistors until the characteristics of the load and the power supply are completely specified.

What do you plan to switch, what are its voltage and current requirements, and what is the power supply voltage?

3

The maximum current is 15amp and i would like to have a supply voltage range of around 9-30volts.

4

Use of bipolar transistors is a very inefficient solution for such large currents. Due to the Vce saturation voltage, you would be wasting on the order of 4V*15 amps = 60 watts in just the PNP output stage alone. You should consider MOSFET drivers instead.

5

something like this:

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