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AC/DC adapter design trends emphasize powerful, yet 'greener' units

Makers of AC/DC adapters are increasing the average efficiency while cutting standby power use and complying with buyers' requirements to provide energy-saving features.

Suppliers of AC/DC adapters in China are striking a balance between high-performance and environment- friendly products. Models that are more powerful, efficient and reliable yet come in smaller form factors are leading R&D and supply.

AC/DC adapter
Shenzhen Flypower's Fly10008G model has 100 to 240VAC 50/60Hz input and 9 to 30VDC output.

The emphasis is on improving transformer performance, while reducing power dissipation in the adjusted tube and losses both in the line and external control circuit of linear adapters. Makers are also decreasing switching, conduction and transformer losses.

With technologies and design for medium- and high-power units maturing, increases in efficiency are now trained toward 50W versions. In compliance with the latest Energy Star standards, a number of companies can make products with less than 0.5W or even below 0.3W standby power.

The roadmap to 'greener' adapters starts with optimizing the transformer from the magnetic core, winding and overall structure. The other essential steps include selecting high-grade components such as rectifiers, filters and switching ICs, and setting their parameters. Choosing the latest power management and control chips and adding systems that reduce energy use such as power factor correction or PFC, lossless snubber network and parallel flow circuit are important factors as well. Any fine-tuning, however, ramps up costs. A 5Vx0.45A output with a 14.1 percent efficiency increase and 0.045W cut in standby power, for instance, would translate to about $0.30 rise in outlay.

With these efforts, the industry in China is forecast to post an annual growth rate of 10 percent in coming years. Total output in 2010 exceeded 1.5 billion units from more than 2,000 suppliers.

Currently, China accounts for 60 percent of the world's AC/DC adapters, fulfilling demand from portable electronic devices. The share is expected to increase as companies consider expanding production capacity to meet robust demand from abroad, especially the EU and North America.

At present, small players can churn out 500,000 units a month, midsize manufacturers between 1 million and 3 million, and large enterprises up to 6 million. Shenzhen Moso Power Supply Technology Co. Ltd has a monthly capacity of 2 million units. Shenzhen Flypower Tech Co. Ltd, which can accommodate orders of up to 900,000 a month, plans to increase output to 1 million in the months ahead. Guanyuda Power Supply Co. Ltd expects 30 percent sales growth this year.

Types & specifications
Hong Kong: Lightweight, trendy units lead AC/DC adapter R&D
Taiwan: Circuit protection R&D target in AC/DC adapter line
Product gallery
Types & specifications

The performance and quality of AC/DC adapters depend on their specifications. These include rated input voltage and tolerance, power output, ripple and regulation accuracy. There are also power density, hold and transient recovery times, temperature coefficient, insulation resistance and voltage, and thermal resistance coefficient.

Products from China come in 3 to 120W series. Some suppliers customize the design to comply with a specific power output, mostly up to 250W. The input voltage is 100 to 240VAC or 90 to 264VAC, while the frequency is 50/60Hz or between 47 and 63Hz.

Models are commonly linear or switched mode, with the latter dominating production and sales. Those classified as external are wall-mount or desktop. Internal units are usually referred to as switching power supplies.

Linear AC/DC adapters are the earliest kind of power supplies in the market. The technology is mature. Integrated modules boast low output voltage ripple and high stability and reliability. Products are classified by voltage regulation, with integrated variants overtaking all other categories for their built-in overcurrent and -heat and short-circuit protection, good reliability, simple connection and easy maintenance.

Linear versions usually require bulky low-frequency transformers and filters, and adjusted tubes as big power draws. These make them heavy and inefficient compared with switched-mode units. The rapid development in the latter's technology has rendered the linear type even more inferior in both performance and price.

At present, switched-mode adapters have an average power of below 12W. The small target market includes cordless phones, electronic organs and certain medical equipment. Products come in small form factor, are lightweight, stable, reliable and efficient, and have a high power density and wide input voltage. The output ripple is also bigger compared with linear models.

Switched-mode variants rectify, filter and adjust the voltage directly from the power grid, controlling it through the switching regulator, and thereby eliminating the need for a low-frequency transformer. A switching regulator's loss is very small, so the efficiency can reach or exceed 95 percent. The category currently makes up 75 percent of the total output in China. Large companies pursue this segment, while small and midsize enterprises manufacture both switched-mode and linear types.

Makers also design protection circuits, including programmable units and those that check polarity and drops in voltage. Some adapters have PFC, voltage regulation and output voltage switching circuits.

Raw materials and components account for 70 percent of production costs. These constitute ICs, power chips, transformers, rectifiers, filters, thyristors, passive components, plastic, metal and casing, which are all sourced locally. Several key inputs, usually for power management, are imported on request.

The major vendors are National Semiconductor, On Semiconductor, TI, Fairchild, STMicroelectronics, Power Integrations and several Taiwan companies. ICs make up more than 50 percent of overall outlay.

Most manufacturers have established long-term relationships with their material providers to ensure a stable supply of key components at favorable rates. The cost of some materials, including plastic, wire, copper and tin, however, increased drastically in 2010.

Several companies managed by boosting production capacity, but others raised quotes by about 5 to 10 percent to avoid losses. Guanyuda adjusted prices by 10 percent in reaction to climbing copper and labor costs. It expects additional movement if expenses continue to grow.

Hong Kong: Lightweight, trendy units lead AC/DC adapter R&D

Compact AC/DC adapters are the main design trend from Hong Kong suppliers. Aesthetic innovations such as semitransparent ABS housing, glossy surface finish and nontraditional enclosures have been introduced. Some models have LED lights for status indication or decoration. Travel versions may come with detachable or retractable universal plugs.

The two key features that are setting some of the latest AC/DC adapters apart are auto-voltage selection and USB integration. Despite the increasing adoption of Micro-USB as the worldwide standard for mobile phone charging, many units continue to adopt the standard USB type A receptacles for wider compatibility.

AC/DC adapters in switching, and linear regulated and nonregulated variants are available in Hong Kong. The power output ranges from 1 to 300W.

The mobile computer segment continues to be the cash cow for the line. Universal and model-specific adapters for notebook and tablet PCs and netbooks are regularly announced. Products targeted at video game applications are also available.

To ensure easy entry into the North America and Europe markets, many of the territory's more than 40 suppliers have developed models that comply with CEC Level V and ErP Level 2 standards.

Goldsphere Industries Co. Ltd has been developing and manufacturing linear AC adapters for varied applications since 1985. Its wall-mounted and desktop versions meet T.V, GS, UL, cUL, FCC and C-Tick requirements.

EDP Worldwide Co. Ltd specializes in power supply and electronic novelty products. It caters mainly to OEM and ODM customers. Among the maker's most popular releases are universal travel adapters with retractable plugs, wide input voltage, short-circuit protection, high maximum load and USB output.

Hip Hing Cable & Plug Mfy Ltd has been offering a range of cables and accessories for A/V, gaming, computer and telecom applications since 1987. It is a veteran OEM provider with a production capacity of more than 2 million units per month.

Taiwan: Circuit protection R&D target in AC/DC adapter line

Circuit protection is the critical R&D issue in Taiwan's AC/DC adapter line. Short-circuit, and overload, -voltage and -heat protection are the most common safety features. A model's weight and dimensions are checked to ensure they match slim and light design trends in target applications.

AC/DC adapters from the island's suppliers are aimed at consumer electronics. Portable devices such as mobile phones, multimedia players and PC products are the mainstream applications, while LCD TVs, industrial PCs and LED lighting are emerging markets. Companies also offer customized models.

Large manufacturers accept orders from big-name brands as an important business strategy. Darfon Electronics Corp., for instance, serves major computer makers HP, Acer and AsusTek. The company also supplies one-stop power solutions, including inductors, inverters and converters.

The AC/DC adapter industry in Taiwan is a mature line with a low technology barrier, making price competition in the low-end sector cutthroat. To lower costs, about 80 percent of companies have set up factories in mainland China to carry out mass production. Manufacturers also apply for ISO certification and improve management skills through customization and co-design services. They implement adequate return and warranty policies as well.

There are about 200 suppliers backed by a strong ICT industry. The notable enterprises include AcBel, Darfon, Delta, FSP, Lite-On and Phihong.

Related reports:
Switching power supplies: Rollouts stress slim designs, greater efficiency
DC-DC converters: Models in compact, efficient, customized configurations drive R&D

AC/DC adapter
Product gallery

Darfon Electronics Corp.

Model: BB451J/BB451K
Description: 45W maximum power; 90 to 264VAC, 47/63Hz input; >5ms holdup time at 110VAC, 50Hz maximum load; short-circuit, overcurrent, -voltage and -heat protection; 89.5x35.6x26.5mm; UL, cUL, CE, T.V, PSE, CCC, CB, PSB

AC/DC adapter

EDP Worldwide Co. Ltd
(Hong Kong)

Model: MPC-N1
MOQ: 3,000 units
Delivery: 25 days
Description: Universal type; 90/250VAC input; 100 to 230VAC output; USB connector; integrated surge protector; compact, for travel use; different plug types, logo imprint services available; CE, RoHS

AC/DC adapter

ENG Electric Co. Ltd

Model: 3A-055WU05XX
Description: Universal type; 5W; 90 to 264VAC, 47/63Hz, 300mA input; 5V, 1A output; >20ms holdup time at 230VAC, 50Hz; 50,000hr MTBF; 0 to 40 C operating, -10 to 75 C storage temperatures; 1-year warranty; UL, cUL, FCC, CB

AC/DC adapter

FranMar International Inc.

Model: FLA045/060
Description: Universal input; cooling via air convection; short-circuit, overvoltage and -heat protection; built-in active PFC; IP67-rated design for indoor or outdoor use; for LED lighting, moving signs; 2-year warranty

AC/DC adapter

Ford Link Mfg Ltd
(Hong Kong)

Model: Linear Adapter 35xx Streamline
Description: 5.5VA maximum power at 3 to 24VDC, 8VA at 3 to 24VAC; 110, 120, 230, 240V; 50/60Hz

AC/DC adapter

Goldsphere Industries Co. Ltd
(Hong Kong)

Model: EI-28
MOQ: 1,000 units
Delivery: 14 days
Description: 230VAC, 50Hz input; 9V, 200mA output; custom designs accepted; T.V, EuP, RoHS

AC/DC adapter

Guanyuda Power Supply Co. Ltd
(mainland China)

Model: A1301-GM-050YYY
Description: 36 to 60W; 100 to 240VAC input; 5 to 48V output; 100mohm minimum insulation resistance at 500VDC; 5% load regulation; overcurrent and -voltage protection; 126x50x32mm; for digital cameras, portable devices; UL/cUL, PSE, GS, BS, CE, CB, FCC, SAA, CCC, BSMI, C-Tick

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Note:This article was originally published by Global Sources, a leading business-to-business media company and a primary facilitator of trade with China manufacturers and India suppliers, providing essential sourcing information to volume buyers through our e-magazines, trade shows and industry research.

All price quotes in this report are in US dollars unless otherwise specified. FOB prices were provided by the companies interviewed only as reference prices at the time of interview and may have changed.

Disclaimer: All product images are provided by the companies interviewed and are for reference purposes only. Those product images featuring products with trademarks, brand names or logos are not intended for sale. We, our affiliates, and our affiliates' respective directors, officers, employees, representatives, agents or contractors, do not accept and will not have any responsibility or liability for product images (or any part thereof) which infringe on any intellectual property or other rights of a third party.

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