Diodes & Protection
Diodes pass current one way. That simple property powers rectification, clamping and a whole family of protection parts.
Diode types​
| Type | Key trait | Typical use |
|---|---|---|
| Standard / rectifier | One-way conduction | Rectify AC, blocking |
| Schottky | Low forward drop, fast | Freewheel, OR-ing, reverse protection, buck |
| Zener | Conducts in reverse at Vz | Voltage clamp / crude reference |
| TVS | Fast, high-energy clamp | Transient/ESD protection |
| LED | Emits light | Indicators (with series R) |
TVS diodes (transient protection)​
- A TVS clamps a voltage spike (ESD, surge, inductive kick) by conducting hard above its breakdown, protecting downstream parts.
- Put one on every externally exposed line: USB, power input, buttons, connectors.
- Choose working voltage above the normal signal, clamping voltage below what the protected part survives; place it right at the connector with a short ground path.
Flyback / freewheel diode​
- Across an inductive load (relay, motor, solenoid), a diode gives the collapsing current a path — without it the back-EMF spikes and kills the driver.
Other protection parts​
- Reverse-polarity: series Schottky (simple) or a P-FET (low loss).
- Overcurrent: fuse, PTC resettable fuse, or an eFuse IC.
- Overvoltage: Zener/TVS clamp, or an active OVP.
Protect at the boundary
ESD and surges enter through connectors. Concentrate TVS/ESD parts and filtering at the board's edge/connectors, with the shortest possible path to ground.
See also​
- Power Management — reverse/over-current/arbiter
- Power Electronics & High-Current