What is a Limited Power Source (LPS) rating?

A power supply that includes a description of “LPS” or “Limited Power Source” literally has limits regarding the maximum permitted output voltage, output current, and power rating. These requirements are described under the IEC standard IEC 60950-1.

IEC 60950-1 [click here https://www.iecee.org/search/?q=60950-1 ].

An advantage to using LPS products is that there are less restrictions due to the lowered risk of fire or electrocution during operation, handling, or a fault scenario. The materials used in LPS power supplies do not need to meet the same ratings as some other classes of power supplies, so the cost of production is often less.

The exact specs (limits) of LPS power supplies have slightly different descriptions depending on the manufacturer, but they all point to the same numerical values. Two examples are shown below.

TDK-Lambda Americas

CUI Incorporated

How is this information useful? Knowing that a power supply has an LPS rating can help reduce costs or possibly result in more purchase options when deciding between multiple products with various agency approvals. Some certifications may not be required for a given application.

To find power supplies with an LPS rating, look for ‘LPS’ under the Approval Agency filter (or similar title) in the power supply categories on our site. Example: AC DC Destop, Wall Adapters [click here https://www.digikey.com/short/z03jqh ]. Product Index > Power Supplies – External/Internal (Off-Board) > AC DC, Wall Adapters > ‘LPS’

More power supply products can be found by searching from our main page: [click here https://www.digikey.com/ ].

Further reading:

(CUI) An Overview of Limited Power Source (LPS) Requirements
[click here https://www.cui.com/blog/overview-of-limited-power-source-lps-requirements ]

(TDK-Lambda Americas Blog) What is a Limited Power Source?
[click here http://power-topics.blogspot.com/2012/06/what-is-limited-power-source.html ]

(MEAN WELL) Power Supply Expert
[click here https://www.meanwell.com/qa.aspx?c=11 ].

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