Linear power supplies are a very familiar power supply since they were the normal standard before switch mode power supplies were introduced into the power supply industry. These power supplies have many benefits and drawbacks depending on the intended application.
Advantages for linear mode power supplies include simplicity, reliability, low noise levels and low cost. These power supplies, also known as linear regulators (LR), have a very simple design in that they require few components making it an easy device for design engineers to work with. This simplistic design makes linear power supplies more reliable because the low complexity level does not allow for many issues to arise. A performance advantage to linear mode power supplies is that they are relatively noise-free. Linear regulators have a low output voltage ripple making them best suitable for applications where noise-sensitivity is essential. A final advantage to linear power supplies is their overall cost-effectiveness because they contain a low number of components making them a preferred power supply option if a linear regulator solution suits the application’s requirements.
Along with the many benefits of linear mode power supplies, there are also drawbacks to linear power supplies. Linear regulators are ideal for many low-power applications so when a higher power is needed, the disadvantages become more apparent. These disadvantages to linear power supplies include size, high heat loss, and lower efficiency levels when compared to a switch-mode power supply. The problem with linear power supply units, when used in a high power application, is that it requires a large transformer and other large components to handle the power. Using larger components increases the overall size and weight of the power supply and can pose a challenge for weight distribution within a given application.
Another downside of linear regulators is the high heat loss that occurs when regulating a high power load. The high output current must pass through the power transistor because of the linear design. This thermal stress demands that linear power supplies use a heat sink to dissipate the energy loss. This can be seen as a drawback depending on how the linear mode power supply is mounted to its system. The final setback of a linear regulator is that it is not as efficient as a switch-mode power supply if there is a large difference between the input and output voltage. It is important to consider many different factors, such as dropout voltage and load voltage, when looking at a linear mode power supply’s efficiency level for your application.
Linear mode power supplies offer many advantages such as a simple design and overall low cost while also having disadvantages like high heat loss and varied, low efficiency levels. When deciding on which power supply to use for an application, it is necessary to look at many elements beyond just size, cost, and efficiency. Fortunately, if an electrical engineer decides to use a linear power supply within their design, they will have a variety of linear power supply units to choose from.
