Input capacitor ripple

Basic RMS uses input voltage, output voltage, and load current. Voltage ripple, derating, and anti-resonance are on the other tabs.

Basic RMSVoltage rippleDeratingAnti-resonance

Input voltage, VOutput voltage, VOutput current, AInductor ripple ratio

Switching frequencyEffective capacitance for rippleTotal ESR, ohm

Total ESR is the bank already in parallel. Single-part ESR is on the derating tab.

Rated capacitanceRated voltage, VDielectric factorBias exponentParallel count, whole numberSingle-part ESR, ohmThermal resistance, K/W

Rated capacitance is the nameplate value. Effective capacitance is the derated result, not the rated value.

Bulk ESLBypass ESLBulk capacitanceBypass capacitance

Worked example

RMS current 4.465143 A

Duty 0.275

D = Vout / Vin

Icin,rms = Iout * sqrt(D * (1 - D))

Worst-case RMS 5 A

Icin,rms,max = 0.50 * Iout. This line does not replace the duty line.

The worked example uses 12 V, 3.3 V, 10 A, and 500 kHz. A 0.40 retention figure for a 22 µF part is a note, not this result.