Zener Diode Calculator
This calculator determines the ideal series resistor value for a Zener diode voltage regulator based on input voltage, Zener voltage, and current requirements. It’s useful for designing simple voltage stabilization circuits.
Series Resistor for Zener Voltage Regulator
Zener Diode Resistor Formula
Where:
- $$R$$ = series resistor (Ω)
- $$V_{\text{in}}$$ = input voltage (V)
- $$V_Z$$ = Zener breakdown voltage (V)
- $$I_Z$$ = minimum Zener current (A)
- $$I_L$$ = load current (A)
This formula ensures that the Zener diode remains in its breakdown region to maintain a stable output voltage.
Zener Diode – Calculation Example
Given:
- $$V_{\text{in}}$$ = 12 V
- $$V_Z$$ = 5.6 V
- $$I_Z$$ = 5 mA = 0.005 A
- $$I_L$$ = 15 mA = 0.015 A
Calculation:
- $$R = \frac{12 – 5.6}{0.005 + 0.015} = \frac{6.4}{0.02} = 320~\Omega$$
Zener diodes are widely used in voltage regulation and protection circuits. By selecting the correct series resistor, you ensure that the Zener maintains its breakdown voltage across varying loads. This calculator provides quick and accurate sizing of the resistor to balance input voltage, load current, and minimum Zener biasing current — critical for reliable operation in power supply and embedded electronics design.