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Options needed 12VDC Automotive (13.2VDC) to 5 and 3.3vdc — Parallax Forums

Options needed 12VDC Automotive (13.2VDC) to 5 and 3.3vdc

Brian CarpenterBrian Carpenter Posts: 728
in General Discussion
Is there a power regulator that you like best for making 5 and 3.3 vdc for propeller project from automotive car battery supply?

thank you

Comments

  • Peter JakackiPeter Jakacki Posts: 10,193
    R-78E5.0-0.5 for 5V and then I like to have a nice smooth 3.3 so I use an ldo after it like an MCP1700
  • localrogerlocalroger Posts: 3,451
    What Peter Said. I have been using those Recom switchers for about a year and they are magic. You will need a couple of 10 uF caps on the input and output for reasons that are in the docs. I tend to use the ones that convert direct to 3v3, but if you need both Peter is right that you should use the switcher to 5V and a LDO to 3v3. This gives you amazing versatility. I've run things originally meant for automotive power from both 5V USB sticks (straight to 3v3) and PLC 24VDC power supplies. They are a bit pricey for production at about USD$5.00 in small quantities, but they cut a lot of headache out for small run projects.
  • Brian CarpenterBrian Carpenter Posts: 728
    do you have a circuit that you use these in? What coil do you use?
  • ErNaErNa Posts: 1,752
    R-78E5.0-0.5 is a drop in replacement for 7805. No other components aside Caps are needed
  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2017-01-01 15:51
    Just use it like a 7805T except you can run it at 0.5A (for the cheaper version) with full 24V input even, and it doesn't need a heatsink of course.


    Here's a schematic from one of my boards, the 100uf is a cheap electro but the 10uF are typically tantalum although I do use ceramics at times. The resistor and diode are a form of filter and isolator and input protection in one, the resistor and capacitor does dampen input transients somewhat and the diode is used both for supply reversal and also to stop any charge from being drained back in case of a "brownout" on the input supply. If you have some big motors that run off your input supply you simply use a larger input cap(s), but not on the output of the regulator for a variety of reasons, just let the regulator handle the regulation. btw, the resistor also acts as a fuse if there is some kind of sustained overload.

    R-78E.png
    R-78E.png
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