Power4all

SEPIC Converter Calculator

Design and analyze SEPIC (Single-Ended Primary Inductor Converter) DC-DC converters for power electronics.

Enter Design Parameters for SEPIC Converter

SEPIC Converter Circuit

SEPIC Converter Circuit

Input Voltage (V_s):

Output Voltage (V_o):

Output Power (P_out) [W]:

Switching Frequency (Hz):

Ripple (%):

Enter all parameters and click Calculate.

SEPIC Converter Examples

Example 1: High-Voltage Step-Down (Matches Excel Sheet)

Given: V_s=325V, V_o=56V, P_out=840W, Ripple=10%, f_sw=50kHz

Duty Cycle: D = 56/(325+56) = 0.148 or 14.8%
Output Current: I_out = 840/56 = 15.0A
Current Ripple (ΔI_L): 0.1 × 15 = 1.5A
Voltage Ripple (ΔV): 0.1 × 56 = 5.6V
Inductor (L1=L2): (325×0.148)/(0.2585×50000) = 0.00372 H = 3724.5 µH
Capacitor (C1=C2): 0.2585/(4×50000×5.6) = 15.87 µF
Load Resistor: 56/15 = 3.73 Ω

Example 2: Step-Up Mode

Given: V_s=12V, V_o=24V, P_out=48W, Ripple=20%, f_sw=100kHz

Duty Cycle: D = 24/(12+24) = 0.667 or 66.7%
Output Current: I_out = 48/24 = 2.0A
Current Ripple (ΔI_L): 0.2 × 2 = 0.4A
Voltage Ripple (ΔV): 0.2 × 24 = 4.8V
Inductor (L1=L2): (12×0.667)/(0.4×100000) = 0.0002 H = 200 µH
Capacitor (C1=C2): 0.4/(4×100000×4.8) = 0.000208 µF = 208 nF
Load Resistor: 24/2 = 12 Ω

Example 3: Moderate Step-Down

Given: V_s=48V, V_o=24V, P_out=120W, Ripple=15%, f_sw=75kHz

Duty Cycle: D = 24/(48+24) = 0.333 or 33.3%
Output Current: I_out = 120/24 = 5.0A
Current Ripple (ΔI_L): 0.15 × 5 = 0.75A
Voltage Ripple (ΔV): 0.15 × 24 = 3.6V
Inductor (L1=L2): (48×0.333)/(0.75×75000) = 0.000284 H = 284 µH
Capacitor (C1=C2): 0.75/(4×75000×3.6) = 0.000694 µF = 694 nF
Load Resistor: 24/5 = 4.8 Ω

SEPIC Converter