Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

[SOLVED] How to find ON current for a LED ???

Status
Not open for further replies.

0by1

Junior Member level 2
Joined
May 10, 2011
Messages
22
Helped
2
Reputation
4
Reaction score
1
Trophy points
1,283
Activity points
1,422
Hi all,

For a LED having Vf=2V, If=20mA,

>Whats the ON current for this LED??
>Is that necessary to limit current to 20mA?? so much current !!!!

Thanks in advance.
 

umesh49

Full Member level 4
Joined
May 29, 2006
Messages
218
Helped
25
Reputation
50
Reaction score
21
Trophy points
1,298
Location
Detroit USA
Activity points
2,633
Its depend on LED specification/charactersics. 20mA should be average DC current allowed and there should be a peak current rating also. If you are controlling the LED with a transistor and PWM at base then Imax*duty should be less than 20mA at 25`C. This average current capabillity will reduce at higher temperature depend on derating curve of LED.

Umesh.
 
  • Like
Reactions: 0by1

    0by1

    Points: 2
    Helpful Answer Positive Rating

alexan_e

Administrator
Joined
Mar 16, 2008
Messages
11,895
Helped
2,021
Reputation
4,158
Reaction score
2,031
Trophy points
1,393
Location
Greece
Activity points
64,377
You can drive the led with a lower current if you want which will result in lower light intensity, there is no problem at all as long as you are satisfied with the result.

Alex
 
  • Like
Reactions: 0by1

    0by1

    Points: 2
    Helpful Answer Positive Rating

0by1

Junior Member level 2
Joined
May 10, 2011
Messages
22
Helped
2
Reputation
4
Reaction score
1
Trophy points
1,283
Activity points
1,422
Thanks Alex and Umesh, got the answer.

consideration factors for ON current of a LED
> it should be bright enough
>life of a LED
>should be less than max. forward current.
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top