Ripple Filter Capacitor Calculator
Compute the required filter capacitance from ripple current, ripple frequency and allowed ripple: mains rectifier (full/half-wave), buck output triangular ripple, and sinusoidal ripple.
Key points
Ripple Filter Capacitor Calculator: Compute the required filter capacitance from ripple current, ripple frequency and allowed ripple: mains rectifier (full/half-wave), buck output triangular ripple, and sinusoidal ripple. Formula: C = I / (K·f·ΔV) | full-wave K=2 · half-wave K=1 · buck K=8 · sine K=2π. Enter parameters on the DD-CAT IDE online tool page to get results instantly, with a calculation-model diagram that updates with the inputs. C = I / (K·f·ΔV): K is the waveform factor — full-wave 2, half-wave 1, buck triangular 8, sine 2π. Rectifier filtering: full-wave ripple = 2× line frequency (50Hz→100Hz), half-wave = line frequency; check ripple current and inrush against the peak charging current for large caps.
Inputs
C = I / (K·f·ΔV) | full-wave K=2 · half-wave K=1 · buck K=8 · sine K=2πCalculation model (updates with parameters)
| Required filter capacitance C | 5 mF | C = I / (2 · f · ΔV) |
| Recommended standard cap (E6, rounded up) | 6.8 mF | ≈ 6800 µF |
| Actual ripple at standard value | 735 mV | Meets ripple target |
| Ripple current (RMS) | 1 A | Approximate for rectifier filtering |
| Capacitive reactance |Zc| | 234.1 mΩ | @ 100 Hz |
| ESR limit | 333.3 mΩ | ΔV / peak ripple current; above this, ESR dominates the ripple |
Engineering notes
- C = I / (K·f·ΔV): K is the waveform factor — full-wave 2, half-wave 1, buck triangular 8, sine 2π.
- Rectifier filtering: full-wave ripple = 2× line frequency (50Hz→100Hz), half-wave = line frequency; check ripple current and inrush against the peak charging current for large caps.
- Switching supplies: smaller inductor ripple ΔIL means smaller output ripple; when electrolytic ESR dominates the ripple, parallel low-ESR ceramics.
- Leave 1.3–2× capacitance margin in practice; choose a voltage rating 1.5–2× the working voltage and verify rated ripple current and temperature rise.
FAQ
- What is Ripple Filter Capacitor Calculator for?
- Compute the required filter capacitance from ripple current, ripple frequency and allowed ripple: mains rectifier (full/half-wave), buck output triangular ripple, and sinusoidal ripple.
- What is the formula for Ripple Filter Capacitor Calculator?
- Core formula: C = I / (K·f·ΔV) | full-wave K=2 · half-wave K=1 · buck K=8 · sine K=2π. The tool returns results instantly using this formula and the selected parameters.
- What engineering notes should I keep in mind when using Ripple Filter Capacitor Calculator?
- C = I / (K·f·ΔV): K is the waveform factor — full-wave 2, half-wave 1, buck triangular 8, sine 2π. Rectifier filtering: full-wave ripple = 2× line frequency (50Hz→100Hz), half-wave = line frequency; check ripple current and inrush against the peak charging current for large caps. Switching supplies: smaller inductor ripple ΔIL means smaller output ripple; when electrolytic ESR dominates the ripple, parallel low-ESR ceramics. Leave 1.3–2× capacitance margin in practice; choos…