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.

Duty cycle

Required number input.

Output current (A)

Required number input.

Compute buck converter input capacitor rms current as Iout x sqrt(D x (1 - D)). 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]

Input capacitor RMS current (A)

The resulting input capacitor rms current returned as a number.

• Capacitance, ESR, leakage, ripple rating, lifetime, and self-resonance vary with frequency, temperature, DC bias, aging, dielectric, package, and mounting. Nominal capacitance alone does not determine in-circuit impedance or reliability.
• 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.

• Decoupling Cap Value

  Compute the decoupling capacitance C = I x dt / dV needed to supply a transient current for a droop time within an allowed droop voltage.

• ESR Power Loss

  Compute capacitor ESR power dissipation as RMS ripple current squared times equivalent series resistance.

• Holdup Cap Value

  Compute the capacitance required to hold up a load from the input voltage down to a minimum voltage for a given time at constant power.