LED lifetime wrt current.

O

omgwtfbyobbq

New Member

• Jul 15, 2007

• #1

If I used an LED at the manufacturer's voltage spec, but the current was less than spec, how would that impact the LED's lifetime?

 

Andy1845c

Active Member

• Jul 15, 2007

• #2

It should give it a longer, happier life. Less current = less heat. Its not usually a good idea to run LEDs at max spec'ed current.

 

audioguru

Well-Known Member

Most Helpful Member

• Jul 15, 2007

• #3

LEDs are operated with current, not voltage.
Each LED has a different forward voltage drop as it operates, it is not a voltage that is supplied to it, it just has that voltage when it has the proper amount of current given to it. The manufacturer's voltage spec for an LED is a range of voltages.

An LED that operates at or less than its max allowed current and temperature will slowly get dimmer. The dimming is less at lower current.

 

O

omgwtfbyobbq

New Member

• Jul 15, 2007

• #4

Hmmm, thanks for the replies. Can LEDs be operated at higher voltages with proportionally less current?

 

things

New Member

• Jul 15, 2007

• #5

yes, but only if you want it to last a couple of seconds, in other words, no

 

things

New Member

• Jul 15, 2007

• #6

i have pumped 20,000 volts into an led, and it lit up!!!! but it didn't work after that

 

O

omgwtfbyobbq

New Member

• Jul 15, 2007

• #7

Lets say I have a LED that requires .24A@3V. Are you saying that if I use .06A@12V it'll only last a couple seconds?

 

audioguru

Well-Known Member

Most Helpful Member

• Jul 15, 2007

• #8

An LED sets its own voltage. It is driven by current, not voltage.

Look at the graph of voltage vs current on the datasheet for an LED. If it is 3.0V at 20mA then its voltage will be about 3.1V at 25mA and 3.2V at 30mA.

Its max allowed is probably 30mA and it will burn out if you apply more than that.

 

Sceadwian

Banned

• Jul 15, 2007

• #9

omgwtfbyobbq: LED's current driven devices, if you're increasing the voltage but the current is going down then there's only two possible ways that can occur, something else (like an external resistor) is dropping the rest of the voltage in which case you're not actually increasing the voltage to the LED, or a tunneling effect is occuring, but this doesn't happen the way LED's are doped

 

O

omgwtfbyobbq

New Member

• Jul 15, 2007

• #10

Ah, I gotcha. Thanks everyone!