Typical IR LED; what is the voltage drop & max current?

[William At MyBlueRoom]

Seems I'm looking in the wrong place on Google for IR LED datasheets. I do recall they can be used at upto 100ma (50% duty cycle?) are they 1.2v drop? 1.7v?

 

[Nigel Goodwin]

Re: Typical IR LED; what is the voltage drop & max curre

Seems I'm looking in the wrong place on Google for IR LED datasheets. I do recall they can be used at upto 100ma (50% duty cycle?) are they 1.2v drop? 1.7v?

You need to look for the specific one you have, try LD274 for one I happen to be using at the moment. I'm running it off 3V (2xAA) from a 16LF628, using an NPN driver with a 6.8 ohm series resistor.

It's normal to pulse tham around 1A, with a fairly low duty cycle.

 

[William At MyBlueRoom]

Thanks Nigel, your experience is helpful as always. Perhaps you could clarify the following spec in the datasheet. Since I'm using 5v does it mean the diode will drop 1.9v

 

[Nigel Goodwin]

Thanks Nigel, your experience is helpful as always. Perhaps you could clarify the following spec in the datasheet. Since I'm using 5v does it mean the diode will drop 1.9v

Looks like it to me!.

 

[ljcox]

The voltage across the LED will be 1.9V with a forward current of 1A. And note the 100 us pulse requirement, ie. the 1A must not be on for longer than 100 us.

With a current of 100 mA it will be 1.3V, note the 20 ms pulse.

Given the brief extract quoted, these appear to be typical figures. The maximums are 1.5 V and 2.5V respectively.

 

[togi88]

What about D ?

 

[audioguru]

What about D ?

D is only one letter, not a word. What does it mean? Dutycycle? Dog? Dirty? Duh?

 

[togi88]

I mean tp/T. Typically what should I set in 100mA 20ms, or 200mA ~10ms, or 1A 100us?
In 20ms 50% or 20%?
Or in for example 500mA ?

 

[audioguru]

I mean tp/T. Typically what should I set in 100mA 20ms, or 200mA ~10ms, or 1A 100us?
In 20ms 50% or 20%?
Or in for example 500mA ?

Again, you do not talk in English.
What do the 3 letters tp/T mean in English words?

Oh, I think you are asking what pulse width for certain LED currents?
The datasheet should say. The example that was posted shows a max of 100mA for 20ms or 1A for 100us.

 

[togi88]

Yes, my english is not the best . I am interested by the pulse width, I[A] and the lighting time (perhaps a typical caracteristics with different pulse width curves). I have some 5mm IR LED at home, they are different types and I dont know the exact type. That's why I ask the typical datas of an IR led.

 

[audioguru]

We do not know the spec's for your IR LEDs.
Buy new LEDs that come with important datasheets.