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.

Soft-start time (ms)

Required number input.

Charging current (µA)

Required number input.

Target voltage (V)

Required number input.

Compute the soft-start capacitance from the charging current and ramp time via C = I x t / V. 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]

Soft-start capacitance (µF)

The resulting soft-start capacitance 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.

• 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.

• Charging Time Hours

  Estimate the hours needed to fully charge a battery at a constant current, including a documented 1.2 inefficiency factor that accounts for taper and losses.