PHYSICS & ELECTRONICS / DIODES / PAGE 39 OF 50
The Zener Diode as a Voltage Regulator
Holding a voltage steady.
A Zener diode is made to operate safely in reverse breakdown. In that region its voltage stays almost constant over a wide range of current, so connecting it in reverse across a load sets that load's voltage.
Original diagram: the zener diode as a voltage regulator
A series resistor is essential. It drops the extra supply voltage and limits the current through the diode. Its value is found from the supply voltage, the Zener voltage and the sum of the Zener and load currents, and the diode power rating must not be exceeded.
- Connect the cathode toward the positive side.
- Check the Zener's power rating.
- For heavy loads use a regulator IC instead.
KEY IDEA
R = (Vin − Vz) / (Iz + IL)Browse all 50 physics and electronics pages | Back to the course index