Comparison: Linear Power Supply vs. Switching Power Supply
Unlike conventional power supplies with 50 or 60 Hz transformers, conversion to higher frequencies requires less magnetic volume for the same power output.
In a switching power supply, the transistor is always either fully blocked or fully open and therefore hardly heats up. This allows high efficiency levels of over 90% to be achieved. The disadvantage is that the circuit must be well shielded due to the internally used high-power alternating frequency to ensure good electromagnetic compatibility, and that a small portion of this alternating voltage is always measurable at the output. This is less disruptive to digital circuits or chargers, but very much so to sensitive amplifiers, for example in radio devices, HiFi systems or EEGs.
| Switching Power Supply | Linear Power Supply |
|---|---|
| More complex circuit technology - high frequency | Simple design - low frequency |
| Shielding required to ensure electromagnetic compatibility | Hardly any interference suppression measures needed |
| Smaller and lighter design for the same energy due to lower magnetic volume of the transformer | Relatively large and heavy due to large transformer |
| Higher efficiency levels up to over 90%, economical in consumption, better for environment and customers | Lower efficiency levels, high energy consumption |
Conclusion
Switching power supplies are the preferred choice for modern electronic devices due to their higher efficiency and compact design. Linear power supplies are mainly still used in applications where low electromagnetic interference or particularly clean output voltages are required.