12 vdc to 5 vdc converter
Posted 08 April 2012 - 12:35 PM
I’ve done a little searching but can’t find a suitable dc to dc converter/regulator: I need 5 vdc @ 2.5a, any ideas?
Posted 08 April 2012 - 01:59 PM
Posted 08 April 2012 - 04:03 PM
Posted 09 April 2012 - 04:53 PM
Are you running at the 4.5 or 6v setting?
I checked and the setting I use is 6v.
Posted 09 April 2012 - 09:22 PM
Posted 09 April 2012 - 09:42 PM
1. There's no mounting holes for the board. Resolution - get a 1/2" strip of thin brass from a hobby shop ($1.00) and make a mounting bracket that's soldered to the bottom of the board. This also provides a good heat sink.
2. I needed two of these in my scope power box. One for 5v (USB) the other for 8v (Canon camera). I decided to simplify the mounting by attaching both to the same heat sink. There's an interaction between the two units that disables the current limiting and locks both to maximum output current, 3A. I also had to electrically insulate the heat sinks from each other, even though the grounds for both boards are all connected to the same ground bus. I still don't understand why this was necessary since the heat sinks are attached to the ground plane of each board and the ground planes are connect at the ground bus. A friend of mine who spent a lifetime designing electronics for aircraft, where interference is a major issue, said that we'd have to set up a test bed with a pair of them to figure out where the feedback between them is occurring.
The same suppliers also have a buck-boost regulator that may be of interest to EQ6 owners. I added one to my power box for the mount and now don't have to worry about low battery voltage to the mount.
Posted 10 April 2012 - 10:37 AM
I put both units on the scope last night and found this cheap ebay converter had a slightly cleaner looking output with less apparent ripple and less high frequency noises.
Unfortunately though when I powered up the device with it (3.3V device ~100ma) the display would flicker when powered by the cheap unit only, and periodically reset on its own.
Maybe my application is too low current for it to perform to spec? Not sure but my display is solid on the Pololu board.
Also I found that when hooking up _the input power only_ to the ebay switcher that I could make a dead short by scraping the wall of the IN+ through-hole with a mini-grabber hook. I need to get the board under the microscope to see if it's not a plated through hole and if there is a middle ground plane exposed inside that hole!
Posted 10 April 2012 - 11:12 AM
If you really want a clean output use a older generation linear regulator rather than a switchmode regulator. The linear regulator will be a lot cleaner of a signal but will be less efficient as a drawback. Either that, or the cleanup of a switch mode high frequency signal can be cleaned by a pi filter. This will remove the high frequency harmonics that bring noise into the system.
Posted 10 April 2012 - 01:07 PM
Posted 10 April 2012 - 06:19 PM
Posted 10 April 2012 - 10:55 PM
...Unfortunately though when I powered up the device with it (3.3V device ~100ma) the display would flicker when powered by the cheap unit only, and periodically reset on its own. ...
For your 3.3V 100mA application:
I'd suggest adding one additional 330uF 20V capacitor on the input side and one additional 220uF 6V on the output side.
(It's based on some suggested values on LM2596 datasheet.)