Buck 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.
Snubber Capacitor
Due to a high Q factor, input LC-filters tend to oscillate. A damping path consisting of an electrolytic capacitor with high ESR can attenuate oscillations.
Input/Output Capacitors
For lower ESR, aluminum polymer capacitors are recommended for bulk capacitors. Conventional electrolytic capacitors are suitable as well.
Input/Output Capacitors
For lower ESR, aluminum polymer capacitors are recommended for bulk capacitors. Conventional electrolytic capacitors are suitable as well.
Power Inductor
REDEXPERT helps you find the best power inductor for your SMPS and provide useful information regarding efficiency and temperature rise.
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.
Schottky Diode
Diode‘s junction capacitance in combination with parasitic inductance of traces can lead to ringing.
Switch
A higher switching frequency will enable smaller Inductors and smaller filter components. However, EMI will increase.
Switch Node
The traces of the switch node have to be as short as possible for reduced EMI.
Short Introduction to Buck Converter
The buck converter, also called a step-down converter, is a a widely used switching regulator topology. The output voltage is always lower than the input voltage with the same polarity.
From an EMC point of view, the input line and the node between the diode, switching controller and power inductor, the so-called "hot node", are particularly critical. The power inductor is the key component of the energy transfer. The power is usually in the range of a few watts.
Reference Designs
RD006 3 W Dual-output isolated auxiliary supply for communication interfaces and measurement systems
Buck simulation in REDEXPERT
Determine the ideal power inductor for your buck converter in a few seconds. Design a Sync or Non-Sync converter. Calculate the total AC & DC losses and thermal performance. Get the most efficient power inductor for your application.
