Diodes: Guardians of one-way conduction in the electronic world

1. Definition and working principle

• byP type semiconductor + N type semiconductorconstitutePN junction
• forward bias: P is connected to positive, N is connected to negative → conduction, current flows smoothly
• reverse bias: Opposite polarity → cut off, current cannot flow

2. Main types and characteristics

by material

• silicon diode: Voltage drop 0.6~0.7V, the most widely used
• germanium diode: Voltage drop 0.3V, suitable for low voltage small signal scenarios

By use

• Rectifier diode: AC to DC, used for power adapters and chargers
• Schottky diode: Low voltage drop, fast switching, first choice for high frequency/power supply scenarios
• Zener diode: Reverse breakdown zone voltage stabilization, protection circuit voltage stabilization
• Light emitting diode (LED): Emit light when energized, used for indication, display and lighting.
• varactor diode: Capacitance changes with reverse voltage, used for radio frequency tuning and frequency modulation

Package form

• Plug-in: DO-15, DO-27
• Patch: SMA, SMB, etc.

3. Core functions and typical applications

• rectifier: AC→DC, core function of power circuit
• switch: High-speed switching, used in logic and digital circuits
• voltage stabilization: Stabilize voltage to prevent overvoltage damage to devices
• Limiting/shaping: Control the signal amplitude and protect the downstream circuit
• Protection and current limiting: Prevent components from being damaged by short circuit and surge impact

4. Key points for selection