Initial surge current in linear LED current regulator.

Status
Not open for further replies.
T

treez

Guest
Hello,
The below linear LED current regulator regulates the LED current to 100mA using LT1086 . The LED is
rated 150mA. For the first 60us or so, the current in the LED goes up to 1 Amp.
Do you know how I can stop this initial surge current, and do you think that it could damage the LED or reduce its lifetime?

LTspice simulation attached, and also schematic.

LT1086 datasheet
http://cds.linear.com/docs/en/datasheet/1086ffs.pdf
 

Attachments

  • LINEAR LED CURRENT REGULATOR_1.txt
    911 bytes · Views: 87
  • LINEAR LED CURRENT REGULATOR_1.pdf
    12.6 KB · Views: 98

You attached a PDF file, not the LTspice ASC simulation file.
Instead of playing with a simulation, why not build the simple circuit and measure its output?
 
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating
thanks, but edaboard doesn't accept .asc files
The .txt file should be saved as .asc, then ltspice can run it.

I will build the cct but don't want to if it has that inrush problem.
The following circuit diverts the inrush into a fet, but I don't really want all the extra components.
(attached)
 

Attachments

  • Inrush diverter.pdf
    13.2 KB · Views: 104
  • Inrush diverter.txt
    2.6 KB · Views: 87
Last edited by a moderator:

In LTspice I see the current spike at the beginning.
Does it also happen in a real circuit?
Does an LM317, LM350 or LM338 current regulator do the same thing?
 
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating
That's a good point. Maybe the LT1086 isn't meant to be a pure current regulator.
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…