Power to the purchaser

Farnell product manager, test equipment and accessories, Maureen Lipps, walks readers through the fundamentals of power supply choice.

Power supplies fall into two major categories: linear and switching. Linear supplies are typically used in specific low noise or low power applications. They can be bulky and inefficient, but their low noise characteristics and simple design suit audio applications, communications and low power consumer electronics.

Switching supplies have superior efficiency and performance. They regulate an output voltage with pulse width modulation, which creates high-frequency noise but provides efficiency in a small form factor. Switching supplies are frequently used in industrial applications.

Power supplies can be further classified by their packaging. External AC power adapters, known as ‘wall warts’ or ‘wall adapters’ are used in low power consumer electronics such as laptops and portable audio devices. Bench power supplies are stand-alone desktop/benchtop units for test and measurement applications.

Which supply for which application?
Three further packages suit different industrial applications: open frame, enclosed, and DIN rail. These are usually switching supplies because of their efficiency and small form factor.

Open frame supplies offer a partial mechanical enclosure as they are often built into end products. Components are placed on a compact circuit board and can be easily installed in devices with existing housings. They are usually small, cost effective and easy to cool. TDK Lambda’s GXE600 series boasts up to 95 per cent efficiency. They suit medical, information technology and communications (IEC 60601-1, 62368-1 and 60950-1 certifications) applications, meeting international product specific IEC standards.

Enclosed frame supplies are covered on all sides, ideal when components need to be protected from dust and moisture. They are often used in hazardous environments and demanding applications. Many models integrate fans. XP Power’s CCH600PS28 offers 90 per cent efficiency and suits industrial and military COTS applications, meeting MIL-STD-461 EMC and MIL-STD-810 shock and vibration.

DIN rails are metal strips designed for attaching electrical and industrial control products. DIN rail supplies simply snap or slide into place on the rail. DIN rails are a cost-effective option that save space by allowing tight configurations. They are frequently used in control panels and electrical cabinets and are typically certified to UL standards for safety and performance. TDK-Lambda’s DRB50 Series DIN rail supply is compact and offers 91 per cent efficiency. This supply is typically enclosed in control panels where it can be isolated from the industrial environment.

Choosing the correct power supply is essential to ensure electronic products run smoothly and reliably. Whether looking to use linear or switching power supplies, external AC power adapters, or open frame, enclosed or DIN rail power supplies, consider how each tool can benefit your design project.