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LED ratings?
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LED ratings?

by magician13134 on Wed Jan 16, 2008 7:44 am

I'm new to all of this, and I'm really confused by the LED ratings. I bought some IR LEDs for this project that had these stats:
Code: Select all | TOGGLE FULL SIZE
Infra Red LEDS
Power Dissipation: 150mW
Peak Forward Current: (Pulse Width=100us; duty cycle=1%)) 1A
Continuous Forward Current: 100mA
Reverse Current: 10uA (Vr=5V)
Reverse Voltage: 5V
Forward Voltage:
1.2V Typ; 1.55V max @ 20mA
Peak Emission Wavelength: 940nm
Viewing Angle: 40°
Radiant Intensity: 4.0Ee Min; 8.9Ee Typ @ 20mA
Lens: Water Clear


Manufactured by: Everlight
Part Number: IR333C/H0/L1


It says 1.55V max @ 20mA but it also says the reverse voltage is 5V and then says the peak current is 1A... Can anyone explain this to me a little more clearly?
Thanks
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by adafruit on Wed Jan 16, 2008 1:16 pm

peak current means you can quickly blast 1A thru the LEDs, but not for more than 100us at a time. if you want the LED to be on all the time (say for night vision stuff) you can only put 20mA thru it.

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by magician13134 on Wed Jan 16, 2008 2:01 pm

So for a TV-B-Gone, it'd be somewhere in between those?
Like, 250mA would be safe?
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by adafruit on Wed Jan 16, 2008 2:23 pm

for tvbgone you could probably go as high as 1A since its only turning on the IR LED for short periods.

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by magician13134 on Wed Jan 16, 2008 4:49 pm

Oh, cool. How can I get the current that high? I'm measuring ~30mA from my microcontroller, I used a transistor attached to my 2 AA batteries and got it up to ~110mA, would increasing the battery voltage do that? Maybe?
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by adafruit on Wed Jan 16, 2008 8:13 pm

its not easy, youd need a transistor driver, or possibly a darlington transistor, but then you'd definitely need a good 5V (?) supply because the transistor voltage drop would be like 1V

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