SEPIC Converter

Connector

Filter Capacitor

Keep DC-Bias and SRF in mind when selecting MLCCs for filtering.

Differential Mode Filter

Differential mode noise < 30MHz is best attenuated by ferrite chokes. SMD ferrites capable of high inrush currents are a reasonable addition.

Input/Output Capacitors

For lower ESR, aluminum polymer capacitors are recommended for bulk capacitors. Conventional electrolyt capacitors are suitable as well.

Input/Output Capacitors

For lower ESR, aluminum polymer capacitors are recommended for bulk capacitors. Conventional electrolyt capacitors are suitable as well.

Coupled Power Inductor

REDEXPERT helps you find the best power inductor for your SMPS and provide useful information regarding efficiency and temperature rise.

Coupling Capacitor

During the off-time of the FET, the entire input current flows through the coupling capacitor. REDEXPERT gives you all the necessary information on temperature rise depending on AC ripple currents.

Switch

A higher switching frequency will enable smaller Inductors and smaller filter components. However, EMI will increase.

Schottky Diode

Diode‘s junction capacitance in combination with parasitic inductance of traces can lead to ringing.

Filter Cut-Off Frequency

The filter’s cut-off frequency should be about one tenth of the converter’s switching frequency. Please consider the SRF of all filter components.

Use the REDEXPERT Filter Designer to design an EMI filter and evaluate the realistic response based on real components.

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Short Introduction to SEPIC Converter

The SEPIC converter is a switching controller topology where the input voltage can be greater than, less than, or equal to the output voltage. The input voltage can vary while the output voltage remains constant.

It is a combination of a boost converter and an inverted buck-boost converter. Key components for energy transfer are either two separate power inductors or a coupled power inductor, each in combination with a capacitor, depending on the design. The advantages are short-circuit resistance and a non-inverted output. The disadvantage is higher complexity, making the design more susceptible.

SEPIC Simulation in REDEXPERT

Determine the ideal power inductor for your SEPIC converter in a few seconds. Calculate the total AC & DC losses and thermal performance. Get the most efficient power inductor for your application.

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