Calculators / Buck converter power stage

Buck converter power stage

Losses in the switches, the inductor, the gate drive, dead time, snubber, core and capacitor ESR, added up across the load range. Synchronous or catch diode, one phase or several, with transient droop and the input-filter stability check that usually gets skipped.

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Design Parameters

bolt Core Parameters

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Input Voltage (Vin) Volts

Output Voltage (Vout) Volts

Output Current (Iout) Amps

Switching Frequency (fsw) kHz

500 kHz

Inductor Ripple (ΔiL) % of I_phase

30%

Output Ripple Target (ΔVout) mV

Typical: 10–100 mV (0.1–1% of Vout)

swap_horiz Topology & Phases

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Rectification Topology

Diode Forward Voltage (Vf) mV

Schottky: 300–500 mV

Number of Phases (N)

memory MOSFET Parameters

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HS Rds(on) mΩ

LS Rds(on) mΩ

Switch Rise Time (t_rise) ns

Switch Fall Time (t_fall) ns

Output Capacitance (Coss) pF

Gate Charge HS (Qg) nC

Gate Charge LS (Qg) nC

Gate Drive Voltage (Vdr) V

timer Dead Time & Snubber

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Dead Time (per edge) ns

Body Diode Vsd V

Snubber Capacitance pF

Set to 0 to disable snubber loss

Snubber Resistance Ω

air Inductor Parameters

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Winding DCR mΩ

Core Material

Steinmetz K kW/m³ convention

α (freq exp)

β (flux exp)

Core Volume mm³

Core Area Ae mm²

Number of Turns (N)

battery_charging_full Output Capacitor Bank

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ESR (per cap) mΩ

Number of Parallel Caps

sensors Current Sense

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Sensing Method

Sense Resistor mΩ

filter_alt Input Filter & Stability

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Filter Inductance (Lf) µH

Filter Capacitance (Cf) µF

Damping Resistance (Rd) Ω

trending_up Transient Response

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Load Step (ΔI_step) A

Max Droop Budget (ΔV) mV

Load Step Slew Rate A/µs

0 = instantaneous step (worst case)

Duty Cycle

—%

Min Inductance
—µH

Min Output Cap
—µF

Peak Inductor Current

—A

RMS Inductor Current

—A

RMS Input Current

—A

Efficiency

—%

Total Power Loss

—W

Output Ripple (actual)

—mV

Inductor Slew Rate

—A/µs

Transient Recovery

—µs

Middlebrook Margin

—dB

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Efficiency vs. Load Current

η (%) swept from 0.01% to 100% of rated Iout. ● marks the rated operating point.

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Loss Breakdown at Rated Load

Proportional contribution of each loss mechanism (mW).

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Ripple Cancellation vs. Input Voltage

Normalized cancellation factor K for N=1–8 phases. Lower = better cancellation. ● marks operating point.

functions Key Design Equations

D= Vout / Vin L_min= (Vin − Vout) × D / (fsw × ΔiL) C_ripple= ΔiL / (8·fsw·√(ΔVout² − ΔV_esr²)) [ESR-aware] C_droop= L·ΔI²·K_slew / (2·Vout·(ΔV_droop − ΔI·ESR)) [ESR-aware] I_peak= I_phase + ΔiL/2 K(N,D)= Dm·(1/N−Dm) / (D·(1−D)) [ripple cancel] η= Pout / (Pout + Σ losses) × 100% |Zin|= Vin² / Pout [Middlebrook neg. impedance]

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These tools and articles give theoretical estimates for educational purposes. Real results depend on component tolerances, parasitics and thermal conditions.