abecedarian 330 Posted January 19, 2014 Share Posted January 19, 2014 As people probably know, I'm looking at making an electronic fuel injection system using the Hercules LaunchPad. One thing I need to do is convert the 12v system to 5v, but do so in a very clean way. The bike has a permanent-magnet alternator charging system with a shunt-to-ground regulator so the voltage can swing from 12 to 15 volts during normal operation, and may drop to 8-9 during starting; it only has a 14 amp/hour battery so doesn't take much to draw it down below 12. I want to source at least 2 amperes as it needs to provide power for the throttle position and manifold absolute pressure sensors, coolant and intake air temperature and maybe a few relays for other things as well as the op-amps handling the buffering between the sensors and the ADC, the VR sensor signal conditioning (MAX9926) circuits and maybe the LM1117-N-3.3 to get 3.3 for the LP. Maybe I could parallel two or three LM1117-N-5.0? Quote Link to post Share on other sites
morry 0 Posted January 20, 2014 Share Posted January 20, 2014 Hi! At these high currents you should consider using a switched power supply. You can create designs easily with TI Webbench http://www.ti.com/lsds/ti/analog/webench/overview.page Maybe you should just check, how much 5V power you really need. It might be a good idea to use 12V relays and switch them with 3.3V driven MOSFETs. Quote Link to post Share on other sites
abecedarian 330 Posted January 23, 2014 Author Share Posted January 23, 2014 Forgot about Webbench. Good point about the relays and MOSFETs too. I'm going to look around at what some of the other ECU projects are doing; I'll probably want reverse-voltage protection and such. Thanks. Quote Link to post Share on other sites
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