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Printer power supply design cuts power draw

Posted: 02 Mar 2007 ?? ?Print Version ?Bookmark and Share

Keywords:printer? power supplies? GreenPoint? ON Semi? Energy Star?

ON Semiconductor unveiled its latest GreenPoint reference design for 40W power supplies used to power desktop printers. Providing active-mode energy efficiency above 83 percent when delivering an output power between 5W and 40W, the reference design achieves a no-load power consumption of 150mW.

Frequency foldback technique
The frequency foldback technique implemented in the design keeps the efficiency of the power supply very high under light load conditions. The combination of these characteristics makes the GreenPoint reference design compliant with most requirements from Energy Star to the Group for Energy Efficient Appliances (GEEA) via the US Executive Order "1-Watt Standby" and the Japanese Eco Mark program.

The reference design enables a peak power of 80W to be delivered. An overpower protection below 100W has been implemented for the entire input voltage range of 88-265Vac to comply with the limited power source (LPS) test.

current-mode controller
The enabling device is the NCP1351, a current-mode controller targeting low-power, off-line flyback SMPS. Based on a fixed peak current technique (quasi-fixed TON), the controller decreases its switching frequency as the load becomes lighter. When the frequency decreases, the peak current is gradually reduced down to approximately 30 percent of the maximum peak current to prevent transformer mechanical resonance. The risk of acoustic noise is diminished while keeping standby power performance.

The device is available today at 32 cents for 2,500 pieces.

- Emily Gleason
eeProductCenter




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