I was hoping some of the more experienced folks here would take a look and see if I made any glaringly obvious mistakes in designing the power supply portion of my circuit.
Some quick notes:
- The "12V" input supply is actually an automotive electrical system.
- D1 and D2 may not be totally necessary, but I feel better protecting from someone connecting the external lines backwards.
- D1 and D2 are rated for 9A forward current.
- The MCU side of the circuit also has a 100nF decoupling capacitor at each power pin.
- The two TVS diode have a breakdown voltage of 15.5V and a clamping voltage of 19V.
- Voltage regulator input capacitor is ceramic.
- Voltage regulator output capacitor is aluminum electrolytic with an ESR of 45mΩ.
- The ATMega328P-AN MCU is only running three inputs (two capacitive touch keys and one reed switch) and one output (the MOSFET you see here).
- MOSFET data sheet: http://www.mouser.com/ds/2/115/ds31738-765013.pdf
- Regulator is ON Semiconductor part #NCP1117DT18RKG, the data sheet is here: http://www.mouser.com/ds/2/308/NCP1117-D-81326.pdf
Unless anyone see anything glaringly obvious that is wrong I'm going to build it and give it a shot!