A semiconductor diode, the most commonly used type today, is a crystalline piece of semiconductor material with a p–n junction connected to two electrical terminals. Semiconductor diodes were the first semiconductor electronic devices.
It has two types of packages, plug-in, and chip.
- Frequently used plug-in package: D0-15, D0-27, D0-35, D0-41, T0-220, etc.
- Frequently used chip package: SMA, SMB, SMC, SOD-123, SOD-323, T0-277, etc.
By recovery time the diode has general recovery, quick recovery, ultrafast recovery, and SCHOTTKY.
In a power supply circuit, the common use is silicon diodes, the voltage is 0.6-0.7V.
- When the current flows from positive to negative, the diode is on.
- When the current flows from negative to positive, the diode is off.
- Average output current(Io). Under the condition of continuous operation of the half-wave rectifier, the average value of maximum half-wave current.
- Maximum reverse working voltage(Vr). When the diode is working, the maximum reverse voltage is allowed.
- Forward direction voltage drop(Vf). When passing rated forward current, the voltage drop between two ends of the diode.
- Reverse recovery time(Tr). When the diode is connected to the reverse voltage, there is no current passing through, at this time, the diode will be an equivalent capacitance, if the forward voltage is turned on at this time, there will be a charging process, the charging time is the reverse recovery time.
- Working temperature(Tj). The working temperature of the common diode shall not exceed 120°.
- Rectifier. Put ac power converts dc power supply.
- Switch. When a forward voltage through, the diode is on, and a reverse voltage through, the diode is off.
- Absorption spike. When a MOS is off, a spike voltage will be generated, the spike voltage passing into the diode, spike voltage absorbed by the diode.