constant current regulator for 5 volt

Discussion in 'The Projects Forum' started by embpic, Jul 12, 2014.

  1. embpic

    Thread Starter Member

    May 29, 2013
    187
    3
    how to provide constant current to output where output is of 5volt.
    I need output of 5volt and 150mA current.I am thinking to make multiple USB charger.
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,100
    3,034
    No can do. You cannot specify both current and voltage without also defining the load. You CAN set a maximum current at a constant voltage, or vice versa. A normal USB arrangement is constant 5V.
     
  3. embpic

    Thread Starter Member

    May 29, 2013
    187
    3
    yes sir load is to charge the mobile means it can take normally i think 100ma to 200ma.
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,100
    3,034
    Right, a variable amount of current as needed to charge the mobile phone. You wrote "constant current", which it is not.

    Most mobile phones require far more than that, I think 500mA, these days. Check the requirements of the phone(s) you need to charge.

    The most common method by far is to use a 7805 voltage regulator integrated circuit. Look at the data sheet and follow what it says. There are more efficient, "better" approaches, but they are not as easy for a beginner. And I should add that the commercially available devices you can buy will cost less and work better than almost anything you try to build. I've built them for fun, but it's not something I recommend unless you want to.

    What is your power source - Car? Home?
     
  5. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    You provide the 5V, but the charging current is controlled by circuitry inside the phone.
     
  6. embpic

    Thread Starter Member

    May 29, 2013
    187
    3
  7. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,779
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    Trying to drive that audio system and charge a phone could be beyond the output capability of your USB port :(.
     
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