I am trying to design a circuit to drive an ignition coil in an automotive application using a microcontroller. The microcontroller operates on a 5VDC input and puts out a 3.3V and 4mA digital signal from its pins. Attached is a picture of the circuit I have so far.
There are a few issues I know I need to resolve:
- I don’t know what model of MOSFET to use here. I’m having trouble using the digikey search and filter functions to figure out what I need. I am pretty certain I need an n channel enhancement mode MOSFET, though.
- I don’t know if I need to add another MOSFET before the one I already have in the circuit to drive it. Since I’m only working with 4mA and I need to drive upwards of 10A to the coil, I feel like I may need another MOSFET in between to step up the power to drive the main power MOSFET.
- I don’t know if I need additional protections added into my circuit. I’ve been reading about flywheel or flyback diodes, adding a resistor and capacitor in parallel with the coil, and zener diodes. These are beyond what I know about electronics.
If you notice anything else wrong with my circuit please let me know. I don’t usually work with these kind of components; I’m used to just wiring everything up to the car battery.
Edit 2: Is an IGBT what I need maybe? This looks like it could do what I want? Having trouble understanding if it meets the specs I need, though. I've never read anything about IGBTs until today.