What is a Zener impedance and how is it calculated?

A Zener diode is a type of semiconductor device that is designed to operate in the reverse breakdown region, maintaining a nearly constant voltage across its terminals (called the Zener voltage) when the reverse bias voltage exceeds a certain threshold. This characteristic makes Zener diodes useful for voltage regulation and voltage reference applications.

The Zener impedance, often denoted as "Zz" or "Zener dynamic impedance," represents the change in voltage across the Zener diode for a small change in the current through it. It's essentially the dynamic resistance of the Zener diode at its operating point and is typically measured in ohms (Ω).

The Zener impedance can be calculated using the following formula:

Zz = ΔVz / ΔIz

Where:

Zz is the Zener impedance (in ohms).

ΔVz is the change in Zener voltage (in volts) due to a small change in Zener current.

ΔIz is the corresponding change in Zener current (in amperes).

Keep in mind that this is a simplified explanation, and the Zener impedance can vary with operating conditions, temperature, and other factors. It's important to refer to the manufacturer's datasheet for more accurate and detailed information about a specific Zener diode's characteristics, including its Zener impedance.