Question
Why is a switching type power supply less expensive and lighter than an equivalent linear power supply?
Answer Options
- A) The inverter design does not require an output filter circuit
- B) The control circuitry uses less current, therefore smaller heat sinks are required
- C) The high frequency inverter design uses much smaller transformers and filter components for an equivalent power output
- D) It recovers power from the unused portion of the AC cycle, thus using fewer components
Correct Answer: C
Explanation
The primary advantage of a switching-mode power supply (SMPS) is its high energy efficiency (typically 80\% to 95\%), which means less heat is generated. This efficiency leads directly to lower cost and weight compared to the traditional, low-efficiency linear power supply architecture.
This is because the switching process operates at very high frequencies (tens of \text{kHz} to \text{MHz}), rather than the 50 \text{ Hz}/60 \text{ Hz} line frequency of a linear supply. This high-frequency operation allows the regulator to use much smaller transformers and filter components (inductors and capacitors) for an equivalent power output. These magnetic and filter components are typically the heaviest and most expensive parts of a linear power supply.
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