Uncovering the Differences Between Linear and Switching Power Supplies



When it comes to powering various types of electronic equipment, it’s important to understand the difference between switching and linear power supplies. Both types of power supplies have their own particular benefits that make them suitable for different applications.


Switching power supplies are more efficient than linear power supplies, primarily because they use high-frequency switching to convert the AC power from the wall outlet into the DC power used by devices such as computers. The switching mechanism allows them to maintain output voltage at higher currents and higher frequencies than linear power supplies, resulting in much more efficient power conversion. Additionally, switching power supplies are considerably smaller and cheaper than their linear counterparts, making them an attractive choice for applications that require space or cost efficiency. Switching power supplies utilize pulse-width modulation (PWM), allowing for an efficient transformation of AC to DC power. These supplies are generally much more compact than linear power supplies, due to the fact that the VA rating of the transformer is lower on a PWM duty cycle. However, this compact size and energy efficiency does come with a cost, as the constantly changed electrical current created by the unit leads to a much higher noise output than linear supplies. Additionally, switching power supplies have the ability to both step up and step down voltage, making them useful for applications that require voltage increase. Linear power supplies cannot do this. Finally, switching power supplies are capable of using different AC input to produce a steady DC voltage, whereas linear power supplies require manual adjustment to fit different input voltages.


Linear power supplies operate by converting incoming AC mains to a low DC output voltage through a linear regulator. The linear regulator works by sensing the output voltage and then feeding back a proportion of that voltage to the external control element to maintain a fixed voltage at the output. Linear power supplies provide tight output voltage regulation, low output ripple and high efficiency. In addition, they are simple to build and are much less expensive than Switch Mode Power Supplies (SMPS).


Overall, while switching power supplies offer versatility with their size, energy efficiency, and voltage change capabilities, they are not suitable for sensitive applications due to the increased noise. On the other hand, linear power supplies remain the better choice for clean, quiet power supply use.







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