current limit

Discussion in 'General Electronics Chat' started by yoosefheidari, Oct 27, 2013.

  1. yoosefheidari

    Thread Starter New Member

    Oct 26, 2013
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    hi
    i'am looking for an ic for drive three 1watt white power led.(boost ic)
    my input voltage is a li-ion battery with a voltage between 3.7 to 4.2
    so output power of ic should be about 3-4 watt.
    can you introduce a good ic to me?
     
  2. TorontoBob

    New Member

    Oct 5, 2013
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    yoosefheidari likes this.
  3. yoosefheidari

    Thread Starter New Member

    Oct 26, 2013
    8
    0
    i just find max77387.but this has two string and support 2 led in each string.but i have 3 led.
    also this ic isn't available in my area.so can i use mosfet's circuits?
    can you introduce me a simple circuit?
     
  4. yoosefheidari

    Thread Starter New Member

    Oct 26, 2013
    8
    0
    any help?
    i need a mosfet's base circuit
     
  5. wayneh

    Expert

    Sep 9, 2010
    12,145
    3,054
    Huh? The MOSFET, if present, is the most trivial part of a constant current driver as you need for LEDs.

    What is your goal, to use a MOSFET or drive your LEDs? What are the specs of your LEDs? Where are you that you cannot get parts? Any other limitations we need to know of? (SMD OK? Thru-hole only? Dimmable?)

    You'll get better feedback with better details.
     
  6. yoosefheidari

    Thread Starter New Member

    Oct 26, 2013
    8
    0
    OK
    i have a li-ion battery with 3.7 to 4.2 voltage and 4800mAh of current.
    i want drive two 3watt led's and led's need 3.6v and 680mA (3.6*0.68=2.448)
    so i should use a step-up ic and i search market's in my area and find LM2577 FOR THIS
    But i need a constant current for lm2577.i need fixed 680ma in output.
    i want circuit of lm2577+constant current.
     
  7. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,771
    971
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