Luxeon emitters

[R.Lewis]

The datasheets for the emitter lll (& star etc) give a recommended max
current (pulse) of 1amp.

Why is this so low?
Is it limited by the bond wiring?
It cannot be a thermal limitation (can it?) because no time is specified -
or have some application assumptions been made.

Anyone any ideas?

 

[Victor Roberts]

On Wed, 2 Jun 2004 19:22:20 +0100, "R.Lewis" <h.lewis-not this

The datasheets for the emitter lll (& star etc) give a recommended max
current (pulse) of 1amp.

Why is this so low?
Is it limited by the bond wiring?
It cannot be a thermal limitation (can it?) because no time is specified -
or have some application assumptions been made.

Anyone any ideas?

Where do you see that the 1 Amp maximum current is for a pulse? My
Luxeon III Emitter data sheet does not seem to list "pulse" at all.
The performance data is given at 1000 ma and also at 700 ma. 1000 ma
provides more light, while 700 ma provides more efficiency. This is on
data sheet DS45 dated 02/04.

 

[R.Lewis]

On Wed, 2 Jun 2004 19:22:20 +0100, "R.Lewis" <h.lewis-not this


Where do you see that the 1 Amp maximum current is for a pulse? My
Luxeon III Emitter data sheet does not seem to list "pulse" at all.
The performance data is given at 1000 ma and also at 700 ma. 1000 ma
provides more light, while 700 ma provides more efficiency. This is on
data sheet DS45 dated 02/04.

data sheet DS25
page 4

Absolute Maximum Ratings....
......Peak Pulse Forward Current (mA) 1000

Note that the max average forward current is also 1000mA!!! -can only be
very smooth DC if the average is the same as the peak.

Is this just poor spec writing or is there something else going on here?

 

[Victor Roberts]

On Wed, 2 Jun 2004 23:15:28 +0100, "R.Lewis" <h.lewis-not this

data sheet DS25
page 4

Absolute Maximum Ratings....
.....Peak Pulse Forward Current (mA) 1000

Note that the max average forward current is also 1000mA!!! -can only be
very smooth DC if the average is the same as the peak.

Is this just poor spec writing or is there something else going on here?

Yes, I see this now. Both the max DC Forward Current and max Peak
Pulsed Forward Current are 1000 ma.

They are obviously stating that the LED should not every be operated
above 1000 ma, even for a short pulse, though they don't say why.
Perhaps the size of the wire going to the die, as I think you stated
earlier. Certainly the die itself has enough thermal mass to sustain a
higher current pulse of some reasonable length.

 

[Steve Eckhardt]

The datasheets for the emitter lll (& star etc) give a recommended max
current (pulse) of 1amp.

Why is this so low?
Is it limited by the bond wiring?
It cannot be a thermal limitation (can it?) because no time is specified -
or have some application assumptions been made.

Anyone any ideas?

My experience is that these LED's rapidly lose brightness if they are
overdriven, even if they are actively cooled. Don't know why, though.

 

[R.Lewis]

My experience is that these LED's rapidly lose brightness if they are
overdriven, even if they are actively cooled. Don't know why, though.
--

Anyone know how to find out ?
I do not know how to contact technical for this at HP/Agilent/Lumileds.