Isolated vs Non-isolated Power Supplies

Isolated vs Non-isolated Power Supplies

What is the difference?

When a power supply is listed as isolated, it is normally referring to input to output isolation. This isolation is typically achieved by the use of a transformer. A non-isolated power supply is generally using a type of chip conversion.

When a multi-output power supply has isolation between the outputs, it means there is an electronic barrier between outputs and not tied to a common ground.

The following explores input to output isolation and non-isolation.

Why use isolated?

Isolated power supplies provide a clear barrier across which dangerous voltages won’t pass. This provides safety. The disadvantage is low efficiencies and the package size is bigger than a non-isolated power supply due the transformer that is needed for isolation.

Why use non-isolated?

A non-isolated power supply is usually >95 % efficient and more compact than an isolated power supply. The down side is, there is no isolation between the input and output. Non-isolated power supplies are commonly board mounted near the load they are driving and are referred to as point of load (POL) power supplies. They are usually downstream from a power supply that is isolated which helps with safety concerns.

Applications

Typical applications that look for isolated power supplies are those that have to meet safety as well as system requirements. Often medical devices require isolation between the input voltage and the output where the load can be a human. In contrast, some applications need non-isolated because of where it is being used, like lighting, appliances, and sensors.

Summary

Advanced Conversion Technology (ACT) has designed and manufactured both types of power supplies over the years for a variety of land, naval, and air applications. An example of our isolated power supply is the SW2512001-54. An example of a non-isolated ACT power supply is the SW2511001-28. Whatever you might need, contact ACT to see how we can best meet your power supply needs.