Ćuk and Zeta converter
CCM two-inductor sizing, coupling-capacitor stress and explicitly checked conduction limits.
Development preview. Check the assumptions below before relying on a result. Calculations run in your browser.
How it calculates
CCM conversion: |VO|/VIN = D/(1−D); ΔIL = VIN D/(L fs)
Assumptions
- Ideal CCM, negligible transfer-capacitor ripple in the inductor slopes, and in-phase triangular winding ripple.
- Transfer-capacitor RMS uses the small-ripple approximation; use a capacitor rated for RMS current and DC bias.
- Ćuk has continuous input/output inductor current; Zeta has continuous output current and pulsating source current. Their shared conversion ratio does not imply identical input filtering.
Worked example
These are the calculator's default inputs. Change any input above to recalculate.
Inputs
- Minimum input voltage
- 9.6 V
- Nominal input voltage
- 12 V
- Maximum input voltage
- 14.4 V
- Output-voltage magnitude
- 5 V
- Minimum load
- 0.02 A
- Maximum / design load
- 1 A
- Switching frequency
- 200000 Hz
- Chosen inductance
- 0.000047 H
- Nominal output capacitance
- 0.0001 F
- Parallel output capacitors
- 1
- Capacitance retained after bias/tolerance
- 0.7
- Each output-capacitor ESR
- 0.02 Ω
- Minimum controller current limit
- 4 A
- Inductor saturation current
- 4 A
- Topology
- cuk
- Second inductor / winding inductance
- 0.000047 H
- Effective transfer capacitance
- 0.00001 F
Results
- Output voltage target
- -5 V
- Chosen L1
- 0.000047 H
- Chosen L2
- 0.000047 H
- CCM duty
- 0.294118
- Input-side average current
- 0.416667 A
- Output-side average current
- 1 A
- First-inductor ripple
- 0.375469 A
- Second-inductor ripple
- 0.375469 A