What Is a Power Supply?
A power supply is a component that converts energy taken from a source (mains, battery, etc.) into the stable and correct voltage/current a circuit needs.
Its Basic Job
The input voltage can be fluctuating or high; the power supply converts it into a fixed output (e.g. 5V, 12V) and holds this value even when the load changes (regulation). So the circuit works safely and stably.
Linear and Switching
A linear power supply dissipates the excess energy as heat; it's simple and noise-free but inefficient. A switching (SMPS) one provides high efficiency by rapidly switching and converting the energy; most modern devices use SMPS. With a ready DC-DC power module this conversion is easily provided without doing the design.
| Type | Efficiency | Property |
|---|---|---|
| Linear | Low | Simple, noise-free, heats up |
| Switching (SMPS) | High | Efficient, small, noisy |
Important Parameters
The output voltage, the maximum current it can give, efficiency, ripple and regulation quality are the basic criteria for choosing a power supply.
Where Is It Used?
Every electronic device: computers, phone chargers, industrial control, adapters and lab bench supplies.
Regulation
A good power supply holds the output steady even as the input and load change. For this job it has a voltage regulator or a feedback control loop inside.
Common Mistakes
- Insufficient current: choosing a supply below the current the load draws lowers the voltage.
- Ripple: using a high-ripple supply in a sensitive circuit.
- Heat: ignoring cooling in a linear supply.
Frequently Asked Questions
Why is an SMPS efficient?+
When is linear preferred?+
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