Use this electronics calculation for a first-pass component, converter, signal, motor, or sensor estimate when the stated operating conditions and units match the device data.

Supply voltage

Required number input.

Zener voltage

Required number input.

Series resistor

Required number input.

Compute the current through a Zener diode in milliamps given the supply voltage, Zener voltage, and series resistor. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Zener current

The resulting zener current returned as a number.

• TVS, varistor, and Zener protection depends on surge waveform, source impedance, clamping current, dynamic resistance, parasitic inductance, temperature, repetition, energy rating, tolerance, and degradation. Nominal voltage is not the protected-node peak.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check the result against the current datasheet and worst-case operating corners, then verify the circuit or measurement with simulation and bench testing where failure matters.

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