Powering lots of led using only usb

Discussion in 'Digital Circuit Design' started by mcskelle, Aug 31, 2017.

  1. mcskelle

    Thread Starter New Member

    Aug 31, 2017
    3
    0
    Hi all, I'm new to this forum and in digital design

    I'm looking for tips and techniques to keep the power usage down in a project that uses many leds/indicator lights. I only have a singles usb-connectors power (500 milliamps).

    Consider this flashy midi controller thing from Akai:



    There must be aprox. 400 rgb leds/single color leds/led indicators powered straight from the usb.

    When i look at rgb-leds (neopixels for instance) they seem to be pretty power hungry unsing 0.2-0.6 milliamps each. The smaller ones and indicators use less i figure, but still I wonder:

    How is this even possible with only 500mA?
     
  2. mcskelle

    Thread Starter New Member

    Aug 31, 2017
    3
    0
    opps: using 20-60 milliamps each!
     
  3. dendad

    Well-Known Member

    Feb 20, 2016
    1,975
    516
    You can use some ultra right LEDs and run them at lower currents. I rarely run LEDs at anwhere near 20mA, unless needed for illumination. Just indicators can be much lower current.
     
    mcskelle likes this.
  4. bertus

    Administrator

    Apr 5, 2008
    18,512
    3,570
    Hello,

    As you are using RGB leds, there are 400 X 3 leds = 1200 leds in the circuit.
    You have about 500 mA available, so each led may consume about 0.4 mA, if you want to light them all (not mentioning the current needed for the controlling circuit).

    Bertus
     
    mcskelle likes this.
  5. mcskelle

    Thread Starter New Member

    Aug 31, 2017
    3
    0
    Can you recommend any specific brands or series. preferable smd's
     
  6. WBahn

    Moderator

    Mar 31, 2012
    22,995
    6,887
    That very much depends on the specifics of what you want/need.

    Try going to Digi-Key or Mouser and using their search tools to see what they offer. Digi-Key has surface mount RGB LEDs that have test currents of 2 mA per color at a cost of about 25 cents in quantities of 2000 (about 90 cents each in onesies).
     
    mcskelle likes this.
  7. Enrico Marcelo 1

    New Member

    Jan 19, 2017
    1
    0
    you will definitely need an LED driver.. there are so much of these available in the market depending on the type of need.
     
Loading...