During ON the inductor current rises with slope $(V_i-V_o)/L$; during OFF it falls through the freewheel diode with slope $-V_o/L$, forming a triangle whose peak-to-peak height is $\Delta I_L$. The output capacitor $C$ integrates this triangular current and smooths it, leaving the residual voltage ripple $\Delta V_{out}$. Raising $L$ or $f_s$ shrinks $\Delta I_L$; raising $C$ or $f_s$ shrinks $\Delta V_{out}$. The ideal buck relation assumes continuous conduction mode (CCM). Light load, ESR, switching loss, and loop compensation need separate checks.
How to read it
The waveform view shows triangular inductor current.
The ripple map highlights insufficient L or switching frequency.
The power view reads load power from output voltage and current.
Learn Buck Converter Ripple by dialogue
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When reading Buck Converter Ripple, where should I look first? Moving Input voltage Vin changes both the plots and the result cards.
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Start with Output voltage, but do not treat the number as the whole answer. Use Buck waveforms to confirm the assumed state, then read Ripple map for the distribution or trend. The waveform view shows triangular inductor current.
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I can see why Input voltage Vin changes Output voltage. How should I judge the influence of Duty ratio D?
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Move Duty ratio D in small steps and watch Current ripple. That reveals which term is controlling the result. The ideal buck relation assumes continuous conduction. Light load, ESR, switching loss, and loop compensation need separate checks. A single operating point is not enough; sweep the realistic scatter range.
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What is Output power breakdown for? It feels like the ordinary curve already tells the story.
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Output power breakdown is for finding boundaries where the condition becomes risky or margin collapses quickly. The ripple map highlights insufficient L or switching frequency. In First-pass L/C sizing for buck converters, the important question is often what happens after a small change, not only the nominal value.
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So if Output voltage is within the target, can I accept the condition?
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Treat this as a first-pass review. It helps with Checking switching frequency against ripple requirements and Confirming CCM at light load, but final decisions still need standards, measured data, detailed analysis, and vendor limits. The power view reads load power from output voltage and current.
Practical use
First-pass L/C sizing for buck converters.
Checking switching frequency against ripple requirements.
Confirming CCM at light load.
FAQ
Start with Output voltage and Current ripple. Then use Buck waveforms to confirm the assumed state and Ripple map to read distribution or bias. The waveform view shows triangular inductor current
Move Input voltage Vin alone, then move Duty ratio D by a comparable amount and compare the change in Output voltage. Output power breakdown shows combinations where margin or performance changes quickly.
Use it for First-pass L/C sizing for buck converters. Instead of trusting a single point, widen the input range and check whether Output voltage keeps enough margin before moving to detailed analysis.
The ideal buck relation assumes continuous conduction. Light load, ESR, switching loss, and loop compensation need separate checks. Final decisions still require standards, measured data, detailed analysis, and vendor limits.
How to Use
Enter input voltage (e.g., 24 V for industrial supplies) and duty cycle (0.4–0.8 range typical for buck converters)
Specify inductor (µH) and capacitor (µF) values; use L ≥ 20 µH and C ≥ 10 µF for 100 kHz switching
Set switching frequency (50–500 kHz) and load current (A); simulator calculates output voltage, inductor ripple (ΔI_L), capacitor ripple (ΔV_C), and continuous-conduction-mode margin
Worked Example
Input: V_in = 48 V, duty cycle D = 0.5, L = 47 µH, C = 100 µF, f_sw = 100 kHz, I_load = 10 A. Output voltage = 24 V (D × V_in). Inductor ripple ΔI_L = (24 × 0.5)/(47×10⁻⁶ × 100×10³) ≈ 2.55 A. Capacitor ripple ΔV_C ≈ 0.96 V (10 A ripple current ÷ 100 µF ÷ 2×π×100 kHz). CCM margin indicates L is sufficient to avoid discontinuous mode.
Practical Notes
Higher duty cycles (>0.7) demand larger L to prevent inductor saturation in automotive/telecom DC–DC modules
Output ripple voltage dominates capacitor ESR above 50 kHz; use low-ESR ceramics (< 10 mΩ) for isolated buck stages
If CCM margin falls below 20%, increase L or reduce switching frequency to maintain stable current-mode control loop