Diodes

Diodes are electronic devices that conduct in one direction. Ideally, they have to block the conduction of current in the reverse direction, but in reality, there is always a small leakage current present.
Due to the presence of impurities in the diode, it gets hot when a large amount of current is passed through.
There are diodes for various applications which focus on a special property of the diode.
- For example:
  - Zener Diode – Works in reverse bias condition. Provide excellent voltage regulation.
  - Schottky Diode – Has low forward voltage drop and high switching speed. Suitable for high-frequency applications and power supply circuits.
  - Silicon Controlled Rectifier (SCR) – Can handle high current and voltage levels. Used for power switching and motor control applications.
  - Light Emitting Diode (LED) – Emits light when forward biased. Used for lighting and display applications.
  - Tunnel Diode – Exhibits negative resistance. Used in microwave oscillators, amplifiers, and detectors.
  - Avalanche Diode – Can withstand high reverse voltage and exhibits avalanche breakdown. Used for overvoltage protection and voltage regulation.
  - Photodiode – Generates a current when exposed to light. Used in optical communication and sensing applications.
  - These are just a few examples, and there are many more types of diodes available for various applications.

The following properties should be looked at in a datasheet. There may be additional details but these are the minimum.

V_F is the voltage drop across the diode when it is conducting current in the forward direction. For example, a silicon diode may have a VF of around 0.7V.
I_F is the maximum current that the diode can handle without being damaged. For example, a diode rated for 1A can handle a maximum current of 1A flowing through it.
V_R is the maximum reverse voltage that the diode can withstand before breakdown. For example, a diode with a VR of 100V can withstand a reverse voltage of up to 100V before it starts conducting in the reverse direction.
P_D is the maximum power that the diode can safely dissipate without getting damaged. For example, a diode with a PD of 500mW can safely dissipate up to 500mW of power without getting damaged.
T_j is the maximum temperature that the junction of the diode can reach without getting damaged. For example, a diode with a Tj of 150°C can safely operate at a maximum temperature of 150°C.
t_rr is the time taken by the diode to switch from forward conduction to reverse blocking mode. For example, a diode with a trr of 50ns will take 50ns to switch from forward conduction to reverse blocking mode.
The package type and dimensions specify the physical size and shape of the diode and are usually given in the mechanical drawing section of the datasheet. For example, a diode may be packaged in a through-hole or surface-mount package with specific dimensions.

Electronic Diodes and Their Part Numbers