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16V -> Powering the Proto Board — Parallax Forums

16V -> Powering the Proto Board

andrusandrus Posts: 4
edited 2010-09-30 16:22 in Propeller 1
I got a Proto USB Board. Is it safe for me to power it with 16V? The data sheet for the LM1086's on the board says that the "maximum input-to-output voltage differential" is 25v for the LM1086-5.0 and 27v for the LM1086-3.3. Now I don't know what this means exactly, so I wanted to post before I fry part of my board.

Thank you,
Mark

Comments

  • ElectricAyeElectricAye Posts: 4,561
    edited 2010-09-29 18:52
    andrus wrote: »
    I got a Proto USB Board. Is it safe for me to power it with 16V? The data sheet for the LM1086's on the board says that the "maximum input-to-output voltage differential" is 25v for the LM1086-5.0 and 27v for the LM1086-3.3. Now I don't know what this means exactly, so I wanted to post before I fry part of my board.

    Thank you,
    Mark

    The data sheet for that board states an input of 6-9 volts

    http://www.parallax.com/Portals/0/Downloads/docs/prod/prop/32212-32812-PropellerProtoBoard-v1.3.pdf

    But I'm sure you already knew that. Right?

    I'm certainly no expert, but I'm guessing that as you go higher than 9 volts on the input, you will start to heat up the regulators as they dump energy to keep things regulated. So probably under only really great heat transfer situations can those regulators actually take that maximum voltage differential. A lot probably also depends on how much current you plan on drawing through them. So I'm guessing it's a hard question to answer because much depends on how you cool the board. But don't take my word for it. Maybe somebody who really knows what he or she is talking about will chime in here. (Hey, at least I bumped your topic back to the top!)

    :)
  • andrusandrus Posts: 4
    edited 2010-09-29 19:32
    Thanks ElectricAye.

    I should have investigated previous forum postings:

    http://forums.parallax.com/showthread.php?t=111496&highlight=lm1086
    http://forums.parallax.com/showthread.php?t=99157&highlight=lm1086

    I wish I had more electrical knowledge. I wanted to run the power from the 16v wall wart I have feeding a bipolar power supply (http://www.musicfromouterspace.com/analogsynth/WALLWARTSUPPLY/WALLWARTSUPPLY.php) -- which in turn powers an op-amp -- to the Propeller board. However, I realize that there are things like current draws (?) and electrical noise (?) I am unfamiliar with... At that stage it might be a poor idea to try to power an Arduino BBB on the same line.

    Maybe I should do the sensible thing and scrounge a second wall wart. Perhaps I could reasonably power both a Propeller Proto Board and Arduino BBB on the same wall wart line in a sensible voltage range?

    If anyone has any suggestions I'd appreciate them -- or directions to reading material on these concepts.

    Thanks,
    Mark
  • Mike GreenMike Green Posts: 23,101
    edited 2010-09-29 20:15
    Dimension Engineering has a series of small switching regulators that can accept inputs up to 30V and produce a regulated output over the range of 6V-9V (as well as 5V). There's one with a 1A output and another with a 3A output. Here's one datasheet. I use one of these to power a Propeller board of mine that requires a 5V regulated supply. This way I have an efficient setup for using any wall-wart from about 8V to 24V with no significant heating.
  • schillschill Posts: 741
    edited 2010-09-30 05:13
    What is the output voltage from your MFOS power supply? I use one in a project with +/- 9V outputs.

    The wall wart used for the MFOS board is typically an AC one - its output is AC and not DC. This is so the supply can provide positive and negative voltages.

    Is the protoboard set up to take an AC input? If not, you should either use the output from the MFOS board (if the voltage is low enough) or get another wall wart.
  • kwinnkwinn Posts: 8,697
    edited 2010-09-30 07:36
    The protoboard will NOT be happy with an AC input. It needs a DC input in the 6-9V range. While it might work with a 12VDC input the regulator may get hot enough to shut down (thermal overload protection). It might even turn off and on several times per second, which can cause some unusual symptoms.
  • max72max72 Posts: 1,155
    edited 2010-09-30 08:09
    The regulators could accept the higher voltage, but they need heat sink.

    Power dissipated as therma energy grows with current usage and voltage drop.

    So you might be able to run it, as long as you ask little current. It worked for me with a 12V supply, but in your case you are probably stretching the limits..
  • andrusandrus Posts: 4
    edited 2010-09-30 16:22
    Schill, last I remember I built the 15v output MFOS power supply using an IBM laptop charger cable instead of a wall wart -- but I think my meter reads the MFOS power supply circuit closer to +/- 16v.

    "Stretching the limits" sounds right. I think it would be better if I got a second power cable for the Propeller. If I were to provide one 9v line to the Propeller, do you think I could also power an Arduino alongside it on the same power line? I realize this isn't a board for Arduino, so maybe the question is akin to powering two Propeller Proto Boards off the same line.

    Thanks for the replies,
    -Mark
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