Switched mode power supplies vs Buck converters


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AVForums Grandmaster
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Dec 24, 2008
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Plumstead, Cape Town
I have gathered from speaking to "those that know" that switched mode power supplies are not recommended for powering audio gear on account of the switching frequency being noisy and this noise either bleeding into the audio signal or causing interference with the audio signal

Many small components now use a 5 volt PSU on account of there being 5 volt components therein

There appear to be 3 ways of getting 5 VDC to your device

1 - A 5 volt plug in switched-mode power supply. Depending on the output power, switched mode power supplies operate in the frequency range from about 10 kHz up to the MHz range. These can generate EMI and electrical noise
2 - A 5 volt linear supply, using a voltage regulator like a LM7805 regulator IC, one drawback being a 1.5amp limit (see circuit diagram below)
3 - A buck converter, which also uses a switched mode device, albeit operating at 150kHz. Higher currents are possible (see pic below)

In the case of 2 and 3, the supply voltage can also come from a 12 volt PSU or a transformer and rectifier

Which of the above is the least offensive and practical for discerning listeners?


This DC-DC module below uses the step-down switching regulator LM2596S to provide a stable power supply. The output voltage is adjustable and can ensure 3A output load current. It operates at 150 kHz and has high efficiency >90%.

Input Voltage : 3V~40V (1.5V higher than the output at least)
Adjustable Output Voltage : 1.5V~35V
Output Current : 3A


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