Connect with us

Power LED from USB

Discussion in 'LEDs and Optoelectronics' started by Nick90, Feb 23, 2013.

Scroll to continue with content
  1. Nick90

    Nick90

    7
    0
    Dec 1, 2012
    Hey there,

    I'm just about to buy this LED, but I want to double check something, I want to power it via 5V USB (using usb main adapter if needed) I was just wondering would I need a driver to power this or would a resistor be enough?

    Also would USB be able to light 2 of these fully?

    Thanks
     
  2. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    5W at 2.5V = 2A so no, you cannot power even one from a USB connector which is 500ma.

    Bob
     
  3. BlinkingLeds

    BlinkingLeds

    180
    0
    Feb 23, 2013
    The max current you can draw of an usb port is 500ma so, no, you need tho find another source of 5v. You can connect them in series so 2.5v * 2 will be 5v, so you don't need resistors.
    those should give as much as an 40-50w incandescent lamp they could turn your whole room red if you place them in the middle. If you don't need that much light you could get some ready usb leds that hook in your usb port.
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,496
    2,837
    Jan 21, 2010
  5. Nick90

    Nick90

    7
    0
    Dec 1, 2012
    Ok thanks everyone!

    So ignore I said anything about USB, imagine it was powered from this, so if I want to power that LED from a 5V, 1A, 5W power supply, what do I need?

    Are there any LED drivers I can buy that will work?
     
  6. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    If you want to power the LED at half power, it is easy. Just a resistor. But note that it would have to dissapate 2.5W so you would want to use a 5W resistor to be safe. The resistor would be 2.5 Ohms at 5W.

    If you want to drive the whole 5W into the LED you would need a DC to DC converter operating as a constant current driver, and it still would not be able to give you 2A at 2.5V because it cannot be 100% efficient.

    Bob
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Similar Threads
There are no similar threads yet.
Loading...
Electronics Point Logo
Continue to site
Quote of the day

-