Diode
A diode is a two-terminal semiconductor part that conducts much more easily in one direction than the other.
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What it is
A diode is a two-terminal semiconductor part that conducts much more easily in one direction than the other.
How students use it
Students use diodes for polarity protection, signal steering, rectifying, and flyback protection around coils or motors when the circuit calls for it.
Pins and power
Anode and cathode. The cathode is commonly marked by a band.
Passive semiconductor. Select current, voltage, and diode type for the job.
Conventional current flows from anode to cathode when the diode is forward biased. Reverse bias blocks current except for leakage and breakdown behavior.
Voltage and safety
Diodes have a forward voltage drop. They are directional, so flipping one changes the circuit behavior.
Use the correct orientation and current rating. A diode installed backward can stop a circuit from working or leave a load unprotected.
Datasheet notes
Important values include forward voltage, maximum average current, reverse voltage, switching speed, and package/polarity marking.
Common mistakes
Ignoring the cathode band, assuming every diode is an LED, choosing a slow/weak diode for a switching job, and forgetting flyback protection for coils.