Power Integrations has announced three charger/adapter reference designs utilizing the company's new LinkSwitch-II family of AC-DC switched-mode power conversion ICs. The new LinkSwitch-II devices utilize highly accurate primary-side control to enable tightly regulated constant-voltage and constant-current (CV/CC) modes of operation with at least 30 percent fewer components than typical secondary-side designs. The new devices exceed the active-mode efficiency requirements of the new ENERGY STAR 2.0 specifications by 10 percent across the entire load range, and consume 90 percent less no-load power than the allowable limit.
Traditionally, switched-mode power supplies use a secondary circuit to sense the output voltage and feed error signals back to the primary-side controller. LinkSwitch-II uses a transformer winding to sense the output voltage, eliminating the need for the secondary circuit. This not only reduces component count by as much as 30 percent, but also improves energy efficiency since secondary-side components consume power. LinkSwitch-II devices further enhance the accuracy of the output voltage and current by compensating for transformer tolerance, input line voltage variations, ambient temperature, and voltage drop in the charger output cable.
Power Integrations has produced a reference design kit, an instructional video and three reference design reports (RDR 157, 158 and 159) to help designers of adapters and chargers benefit from LinkSwitch-II's simplicity and elegant design. A new reference design kit (RDK-160) includes all three complete designs and is intended for use by anyone trying to build a CV/CC adapter under 5.5W.
The first design (RD-157) complies with the China Charger standard for CV/CC cellphone chargers, which has been mandated by the Chinese government. The new design is accurate, highly efficient, features low no-load power consumption and requires the fewest components of any charger available today.
The second design (RD-158) is a high-power cellphone charger for high-end cellphones, PDAs and other portable, personal devices that need significant power to charge voracious lithium-ion power packs very quickly. It offers the same accuracy and efficiency as the other reference designs while providing 5.5W at 5V, +/-250mV.
The final design (RD-159) is an adapter for cordless phones. Cordless phone adapters present unique design challenges since they are electrically connected to the telephone system, potentially worsening the effect of lightning strikes and other high-voltage surges and transients which may damage the equipment. The RD-159 design can withstand 10 kV of surge, yet seamlessly and reliably provides power to the phone with an accuracy of +/- 250mV.
As well as being extremely energy efficient, all LinkSwitch-II family members are produced in Halogen-free, RoHS-compliant packaging, which is increasingly being demanded by key OEM customers and their power supply sub-contractors.
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