EPR-00011 - 70 W Adapter 22-Jan-01
Page 4 of 46
Power Integrations Inc
Tel: +1 408 414 9200 Fax: +1 408 414 9201
ww: http://www.powerint.com
1 Introduction
This document is an engineering report that describes a universal input power supply
that utilises a TOP249Y. This supply is an off-line flyback converter that operates in
continuous mode. Below is a list of notable features:
• Very compact design: (4.1”×2.25”×1.06” internal box dimensions)
• High power density - 7 W / inch³
• Full output power in sealed enclosure at 40°C ambient
• High efficiency: 84% (85 VAC), 89% (230 VAC)
• Low no-load consumption: 350mW (115 VAC), 500 mW (230 VAC)
• Low value input capacitor: extended maximum duty cycle allows 2µF/W
• Power limited during overload: overload output current < 5 A at 19 V
• Primary side soft-start: minimizes component stresses during start-up
• Low EMI due to frequency jittering: meets CISPR22 B / EN55022 B with
output earthed
• Line under voltage sense: no output glitches on power up or power down
• Line over voltage shutdown: extended line surge protection
• Hysteretic thermal shutdown: supply automatically recovers when fault is
removed
• Low component count: simple circuit and design
• Single sided PC board: no plated through holes
• No surface mount components required
This board demonstrates the basic performance features and the increased power
capability of the new family. It was designed to allow testing within the
enclosure of a commercial laptop power adapter. This enclosure was used for the
thermal testing in section 9.
This document contains the power supply specification, schematic, bill of materials and
transformer documentation. Typical operating characteristics are presented at the rear of
the report and consist of performance curves and scope waveforms
