Electrical Characteristics of Electroluminescent Diodes
The characteristics of electroluminescent diodes are very similar to those of commonly used rectifier diodes. The increased bandgap of electroluminescent semiconductors can slightly increase the "bending" voltage in the low impedance forward direction. It should be noted that semiconductors for lamps generally have to be operated with the power supply current, otherwise their current must be limited by a series resistor. Under reverse voltage, the lamp will have a high impedance, up to the breakdown voltage. This breakdown voltage ranges from 5 volts to 25 volts. If the reverse voltage is limited to this value, there will be no adverse consequences due to wrong connection.
Forward current limitation is generally caused by the temperature rise of the device. It can withstand short-term forward current surges or can be used in pulse repetitive currents. When a tungsten filament incandescent lamp is powered on, the initial surge current is several times greater than the normal operating current. This is the only effect that can be compared with electroluminescent diodes, and it should be related to the capacitance of the p-n junction. However, due to the low capacitance of the p-n junction, it may decay within one microsecond.
The rectifying characteristics of semiconductors are very suitable for manufacturing logic components. This has obvious advantages in the design of program alarm indicator circuits.