Zener Diode Calculator

Calculate series resistance and current values for Zener diode voltage regulator circuits. Design stable voltage regulation with proper component sizing.

Zener Voltage Regulator Circuit

    Vin ──┬─── Rs ───┬─── Vout (= Vz)
          │          │
          │          ├─── RL (Load)
          │          │
          │       ┌──┴──┐
          │       │  Z  │ Zener Diode
          │       │  D  │
          │       └──┬──┘
          │          │
          └──────────┴─── GND
          
    Rs = (Vin - Vz) / (IL + Iz)
    Where: IL = Load Current, Iz = Zener Current
V
V
Ω
mA

About Zener Diode Voltage Regulators

Zener diodes provide simple voltage regulation by maintaining a constant voltage drop when reverse biased. They're commonly used for low-power voltage regulation.

Common Zener Voltages:

  • 3.3V: Logic circuits, microcontrollers
  • 5.1V: TTL logic, general purpose
  • 6.8V: Op-amp supplies
  • 12V: Automotive applications

Design Guidelines:

  • Maintain minimum Zener current (typically 5-10mA)
  • Consider power ratings of components
  • Use standard resistor values
  • Add filtering capacitors for better regulation

Limitations:

  • Poor efficiency for large voltage differences
  • Limited current capability
  • Temperature coefficient affects stability
  • Not suitable for high-power applications