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Zener Diode Resistor Calculator
Calculate the series resistor range for a Zener diode regulator using input voltage range, Zener voltage, load current, and minimum/maximum Zener current.
Input Parameters
Results
Equations Used
Rmax = (Vin_min - Vz) / (Iload + Iz_min)
Rmin = (Vin_max - Vz) / (Iload + Iz_max)
Iz = (Vin - Vz) / R - Iload
Pz = Vz × Iz; PR = Iseries² × R
Frequently Asked Questions (FAQ)
Q1: What does a Zener resistor calculator do?
It finds a series resistor range that keeps the Zener diode in regulation without exceeding current limits.
Q2: Why do I need Vin minimum and maximum?
The resistor must keep enough Zener current at low input voltage and avoid excessive current at high input voltage.
Q3: What happens if the resistor is too large?
The Zener may not reach its minimum regulation current under load.
Q4: What happens if the resistor is too small?
The Zener diode and resistor may dissipate too much power at maximum input voltage.
Q5: Is a Zener regulator good for high current loads?
No. Zener shunt regulators are usually best for low current references or simple clamps.
