The Problem :

When designing a Switch Mode Power Supply (SMPS), one common issue is noise interference—unwanted electrical signals that can disrupt the operation of sensitive equipment. This is especially crucial in audio, communication, and precision electronics. The good news is that with the right design adjustments, you can significantly reduce this noise.

The Solution :

SMPS works by switching components rapidly, and this switching can produce high-frequency noise. This can be heard as a buzzing sound in audio devices or cause erratic behavior in digital circuits. The solution lies in improving filtering and shielding techniques in your design.

Practical Example :

Let’s say you’re building a power supply for a home audio system. Without noise filtering, your system could pick up buzzing from the power supply. To solve this, use low-pass filters (capacitors and inductors) at the output to smooth out the voltage, reducing the high-frequency noise. Additionally, ensure the power lines are properly shielded to prevent external interference.

Sample Calculation : 

To select the right capacitor for filtering, use the formula for a low-pass filter:

f = 1 / (2πRC)

Where f is the cutoff frequency, R is resistance, and C is capacitance.

If your system operates at 100kHz and you choose a resistor value of 100Ω, you would need a capacitor of approximately 15.9nF to filter out the high-frequency noise.

Product Suggestion :

For high-quality components, consider using MOSFETs and flux that are specifically designed to handle noise issues.

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