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6 Key Considerations for Selecting an External Power Supply

April 7, 2020 by Maggie McNeal - 5 Minute Read

6 Key Considerations for Selecting an External Power Supply

In This Post...

  1. System Power Requirements
  2. Package Type – Desktop or Wall Plug?
  3. Dc Plug and Cable Options
  4. Efficiency Regulations, Safety Standards, and Agency Marks
  5. EMI and EMC
  6. Branding and System Integration
  7. Conclusion

1. System Power Requirements

The first consideration when selecting a power supply is determining your system’s power requirements. Understanding the wattage, voltage, and amperage your system load requires is essential for the operation and safety of your end system. This includes asking questions like, “does my system operate at a constant power level and what are the minimum and peak power requirements?” If you are unsure or have questions, CUI Inc’s in-house engineering expertise can help.

2. Package Type – Desktop or Wall Plug?

External power supplies are generally offered in two package types: desktop or wall plug (fixed or multi-blade). For many applications either option will work. However, there are some reasons why you may select one over the other:

  • Wattage Ranges: In general, desktop adapters are suited for higher wattage applications, while wall plug adapters are suited for lower wattage applications. Desktop adapters typically have larger case sizes and therefore offer higher output power options.
  • Global Markets: If you plan to take your product or design to market in multiple regions, multi-blade wall plugs and desktop adapters are a great choice. The modularity of the ac blades (multi-blade wall plugs) and ac cords (desktops) allow you to use the same power supply and simply swap the blade or cord in order to meet the end market's plug standards.
  • Ground Reference: Desktops offer the option of three conductor (ground referenced) or two conductor (floating output voltage) ac input cords. Wall plugs are available only with two conductor ac inputs (floating output voltage).
  • Size and Portability: If the adapter is highly visible in your design or if it will be used in a portable application, you may care about the aesthetics, size, and weight of the package. Adapters with GaN technology can help reduce the size and weight of the power supply.
Illustration of adapter package types

3. Dc Plug and Cable Options

For an external adapter to power your design it needs a method of plugging into your system. If the receptacle or jack has already been selected, this will determine which dc plug you choose. One of the most common options is a 5.5 mm x 2.1 mm or “P5” dc barrel plug (5.5 mm OD, 2.1 mm ID, 9.5 mm L). CUI’s standard plug options include barrel plugs, USB, EIAJ, DIN, stripped and tinned, as well as locking and right angle options. If these don’t meet your needs, we can work with you to implement your own plug onto the adapter.

In addition to the dc plug, you’ll want to ensure the dc cord meets your needs. Is it long enough to reach your product? Does it have the desired appearance and pliability? It is important to understand that modifying the dc cord can impact both efficiency and safety regulations.

Illustration showing dc plug options

4. Efficiency Regulations, Safety Standards, and Agency Marks

Making sure you’ve considered the end market where your system will be implemented is critical. Many countries have efficiency standards which regulate the amount of energy that may be ‘wasted’ by external power supplies. Whether it’s Level VI (US), CoC Tier 2 (EU), or ErP Lot 7 (EU) efficiency standards, CUI offers compliant models and can help you navigate the complex and dynamic regulatory landscape.

In addition to efficiency standards, it is imperative to make sure your adapter has the proper safety standards for the end application. For example, medical products need the 60601-1 certification and products for ICT/AV applications need the 62368-1 certification.

Many countries require agency marks which are unique to that country. Specialized design and testing is sometimes required to obtain these country-specific certifications. CUI has the experience and knowledge to work with you to meet your country-specific agency mark needs.

5. EMI and EMC

Many electronic products offered for sale are required to meet EMI and EMC (Electromagnetic Interference and Electromagnetic Compatibility) regulatory requirements. These requirements ensure that your product will not interfere with the proper operation of other products and similarly that the proper operation of your product will not be affected by other products. Although CUI external power supplies are certified to meet EMI and EMC regulatory standards, it is probable that your system (including the power supply) will also need to be tested and certified.

6. Branding and System Integration

Another important consideration and question to ask is, “how well will the adapter aesthetically integrate with my system?” If your design has a desired look-and-feel and you care about the customer experience of your product, then don’t let the adapter be an afterthought. If your product has been intentionally designed with a specific color, then a black adapter may not integrate well. Consider color, texture, packaging, and even adding your logo to the power supply. CUI specializes in a range of customizable branding options.

Illustration showing customer logo placement on adapter

Conclusion

Selecting a power supply for your new product is not a difficult task, but there may be subtle issues that affect the selection process. By working with an experienced power supply company, such as CUI, you can ensure that your power supply not only properly supports the operation of your product but also enhances the value of your product for your customer.

Categories: Product Selection

Additional Resources


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Maggie McNeal

Maggie McNeal

Product Manager

In her time with CUI, Maggie has gained extensive knowledge of both the sales and technical aspects of the power supply industry. In her role, as Product Manager of the external adapter portfolio, she enjoys working with customers to take a project from concept all the way to market release. Outside of the office she spends time with family and friends, appreciating the Pacific Northwest and all of its glory.

 
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