How does a zener diode work?

Answer 1

The silicon is doped to give a very specific and very precise reverse breakdown voltage, that is also very low compared with normal silicon rectifier diodes.

Zeners are operated in the reverse mode, not forward biased. When the reverse voltage is applied current flows through the diode (breakdown mode), and if you try to apply a higher voltage, the diode will simply draw more current, maintaining that breakdown voltage.

You can buy zener diodes in a variety of fixed voltages anywhere from 2.7 volts, all the way up to 150 volts. 5.6 volt and 6.2 volt zeners are common values.

Some zeners are classified as regulators. They are rated for high power (0.5W, 1W, 5W, 10W and up). They can handle lots of current and are used as power supply regulators to maintain whatever voltage the zener is rated for.

Some zeners are classified as references. They are not designed to handle lots of power, but a steady low current (like 1 mA) to provide a stable reference voltage for other components. Most reference zeners are also very stable over temperature, providing an accurate reference voltage.
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Answer 2

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