The circuit symbol and the characteristic curve of infrared light emitting diode,
as shown below. Anode (P pole) with positive voltage, cathode (N pole) voltage is applied to the negative, voltage diode with forward voltage at this time, but also have a positive current, to supply the energy of the infrared light emitting the light beam, the light conditions is same with the light-emitting diode (LED), but the infrared is not visible. In general, the drive voltage of infrared light-emitting diode (IR LED)with GaAs is 1 volt. the drive voltage of IR LED with gallium is 1.8 volt. the green emitting diode voltage as 2.0V.After the input voltage exceeds the general voltage,the current will increase rapidly, at time the effect of input voltage is large by the temperature around. when the temperature is higher,There was a decrease in the input voltage when the temperature is high, conversely, the starting voltage is reduced.

Infrared light emitting diode current – voltage characteristic
Infrared light emitting diode working in reverse voltage, only a small leakage current, but the reverse voltage exceeds the breakdown voltage, immediately generated a lot of current, will make the element burnout, general infrared diode reverse voltage is about 3~6V, when in use, try to avoid this happening.

Heat Loss

The heat loss of infrared light-emitting diodes, voltage VF is applied for infrared led, current generated by the IF accumulation, except for a small part of the energy as the emission of light, heat and radiated mostly formed, heat emitted by the so-called loss.