London — As energy conservation looks set to be a cornerstone in combating both climate change and energy scarcity, Power Integrations has developed the answer to getting rid of the power hungry external adapter while at the same time dramatically reducing its size — a low-profile version of the company's popular TOPSwitch-HX family of AC-DC power conversion ICs.

A small package combined with the best-in-class efficiency and high operating frequency of TOPSwitch-HX enables slim, compact, and lightweight power supplies from 20 to 100 W that comply with the upcoming ENERGY STAR® 2.0 specifications. Typical applications include adapters for notebook computers, as well as power supplies for LCD monitors and flat-panel TVs, in which slim form factor and high efficiency have become critical design criteria

A reference design for a 65 W notebook adapter from the company demonstrates the effectiveness of the device — coming in at only slightly larger than a standard deck of playing cards, while complying with upcoming ENERGY STAR® 2.0 specifications for external power supplies. The reference design utilizes a TOP261 chip in the newly developed eSIP-L package, which is based on a "L" shaped lead-bend that allows the company's eSIP package to lie flat against the printed circuit board with the heatsink pad facing upwards. The device stands just 2 mm above the board providing plenty of space for a heatsink and enabling extremely slender power supply designs

The TOP261 IC used in the reference design combines a 700 V switching power MOSFET with controller and supervisory functions into a single monolithic IC, reducing the need for bulky heatsinks required in designs using traditional TO220 packaged MOSFETs and discrete controllers. It also eliminates the need to encase the electronics with thermally-conductive potting compound. The package's 90-degree pin deflection enables the PCB, chip and heatsink to lie parallel to each other, while the high switching frequency of TOPSwitch-HX removes the need for an expensive planar type transformer. This, together with Power Integrations' proprietary transformer design, greatly reduces both the cost and size of the notebook adapter.

The eSIP-L package delivers the same thermal performance as the older TO-220 package but with a much lower profile. Until now, slim power adapters have tended to be sold after-market and use exotic technologies and even potting compound to achieve acceptable thermal performance — they're expensive. The combination of TOPSwitch-HX with the new low-profile lead-bend package makes it possible to build slimline adapters — just 15 mm thick — using standard wire-wound transformers and simple manufacturing techniques at a cost similar to a standard laptop adapter brick.

TOP258LN, TOP259LN, TOP260LN and TOP261LN devices suitable for slim adapters from 20 W to 100 W power levels are available in the new eSIP-L package style immediately.

To learn more, Power Integrations' Green Room web site (www.powerint.com/greenroom) contains information on the issue of energy waste from inefficient power supplies, as well as tips on designing products that minimize the amount of energy wasted by household and office electronics.