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.

Bus voltage (V)

Required number input.

NTC cold resistance (Ω)

Required number input.

Compute the peak inrush current through an NTC inrush limiter as the bus voltage divided by the NTC cold resistance. 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]

Peak inrush current (A)

The resulting peak inrush current returned as a number.

• Power-supply ripple, hold-up, inrush, efficiency, and loss calculations depend on line range, load transient, switching mode, capacitor bias and ESR, rectifier conduction interval, control limits, temperature, and component tolerance. Safety, stability, EMI, and fault behavior require separate verification.
• 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.

• Contactor Coil Current

  Calculate DC contactor-coil steady current from applied voltage and DC coil resistance; do not use this for AC inrush or inductive impedance.

• Gate Peak Current

  Compute the peak MOSFET gate current as the gate driver voltage divided by the gate resistor.

• Motor Starting Current

  Estimate DC motor current at startup as applied armature voltage divided by winding resistance, before back EMF develops; drive current limiting is excluded.