main part of the LED is also a PN junction, but after the LED is turned on, its voltage drop is general about 2V, and some LEDs can reach 3V. The voltage drop of ordinary diodes is about 0%5V, such as Schottky diodes.
Gaisma izstarojošas diodes ir parasti lietotas kā indikatori. Piemēram, the power indikators and the communication indicator, for example, when the serial port is sending and regreving data, the LED flashes to indicate that the data is being sent and received.
In circuit design, a current limiting rezistors vajadzētu be connected in series. How determine the value of the current limiting resistance? First, we should know the forward voltage and current of LED. The forward voltage of a certain LED is 2.5V, and the forward current is is 5mA. This forward current has a value range. If the current is too large, the diode may be burned. If the current is pārāk mazs, the spilgtums of the LED is not enough.
Šie parametri var var atrast in the LED Data Book.
Pieņemsim ka the DC spriegums is 5V. Atņemt diode spriegums piliens no 2.5V no 5V. The atlikušais 2.5V is dalīts ar the current of 5mA. The resistance is equal to 500 omi.
Tāpēc, a 500 ohm pretestība is required in series in the circuit.
