I have a load powered by a 12V source. The load can draw up to ~2A:
The load has "on and off" modes, but it still draws ~40mA when in "off" mode. I want to switch the load from an MCU to save power when the whole system is off, so I'm looking at adding a transistor:
I'm researching what transistor would be suitable. The TIP31 looks like a suitable candidate, but I believe I need to calculate the thermal requirements. I think I can probably follow this guide for the calculations, but I need to know what the voltage across the transistor (Vce) will be, and that's where I'm stumped.
How can I determine what the voltage will be at the transistor's collector? It seems so simple but my electronics knowledge is fairly basic. How can I calculate or measure this (before buying the transistors)?
Apologies if I've left off any necessary details. Just comment and I'll add them if I have.