Re: Pulsing IR LEDs - determining max drive?

Steve Noll wrote:
How does one determine the maximum safe pulse width, duty, and current
one can apply to a IR LED?

Let's say it's a more or less ordinary 880 or 940 and the manufacturer
has listed its typical operating specs at a 20 mA drive, but has no
higher power pulse specs. Is there a test for determining what pulsed
operation ratings can be assigned to the LED, like, the peak pulse
current that if applied for x hours the LED output is not permanently
degraded by over y percent? How do LED manufacturers determine pulse
drive specs?

Take a look at the spec *** at:
http://www.optodiode.com/pdf/OD100.pdf
That's the data*** for a nominal 100mw 880nm LED and gives duty cycle curves. This particular diode is rated at 500ma for 100mw CW output (with heat sink) and 10 amps for 10 microsecond pulses at 1 second or less repetition at 1.3 watt output.

I've only used some in pulse mode synced with CCD camera shutters to reduce image smearing while keeping the average power consumption and the effective illumination roughly constant. Thats at a 30 hz pulse rate. I haven't tried to push the limits.

For details of how they determine the curves the manufacturer's tech reps would most likely discuss it with you. If not your other choice is to do some destructive testing.
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