Typical IR LED; what is the voltage drop & max current? - Electronic Circuits Projects Diagrams Free

William At MyBlueRoom · 19th April 2006, 04:19 AM

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** · 19th April 2006, 09:21 AM

Quote:

Originally Posted by 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?

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 · 19th April 2006, 01:29 PM

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** · 19th April 2006, 03:44 PM

Quote:

Originally Posted by 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

Looks like it to me!.

ljcox · 20th April 2006, 12:51 PM

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.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

19th April 2006, 04:19 AM	#1
William At MyBlueRoom	Typical IR LED; what is the voltage drop & max current? 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? Attached Thumbnails __________________ Bill Home of the Firefly PIC Tutor Inchworm ICD2 http://www.blueroomelectronics.com

19th April 2006, 01:29 PM	#3
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 Attached Thumbnails __________________ Bill Home of the Firefly PIC Tutor Inchworm ICD2 http://www.blueroomelectronics.com

20th April 2006, 12:51 PM	#5
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. __________________ Len