[sdiy] LED maximum peak current

[Happy Harry]

Hi Martin:

An old Litronix (Siemens) app note on multiplexing LED displays
suggests a (up to) a factor o 5x perceived brightness using duty
cycles of 1-2% and peak currents in the 50-100mA range... and that
a 10uS pulse / 100mA was about the top value in 1982 technology.

Probably a little better these days ???

H^) hary

>From: Czech Martin <Martin.Czech at Micronas.com>
>To: "Sdiy (E-Mail)" <synth-diy at dropmix.xs4all.nl>
>Subject: [sdiy] LED maximum peak current
>Date: Thu, 11 Oct 2001 13:01:51 +0200
>
>I want to build very bright LED indicators.
>Now, the normal spec is average current , e.g. 20mA.
>If I use transients, this can be a lot more.
>I remember my first design project as EE, it was an "inherited"
>design that should send IR telegrams. It had three integrated transitors
>on it, each 30000um wide (this IS substantial) and could
>deliver peak currents up to 1A into each of the three IR
>LEDs. The current was regulated.
>
>Now I want to do something similar, but I don't wat to do
>the current servoing in a discrete design for obvious reasons.
>I want to use the internal parasitic resistance of the
>LED.
>Do red (very bright) LEDs have the same current tolerance,
>i.e. 1A for a single pulse?
>What pulse rate and duty cycle is needed to make the apearent
>brightness as large as possible?
>
>Any LED expert on the list?
>
>m.c.


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