Power Integration

Demoboard RDR-201

Reference Design Report for a 6 W Constant Voltage (CV) Adapter Using LNK625PG

Topology: Flyback
Input Voltage (min.): 90.00 V
Input Voltage (max.): 265.00 V
Output 1: 5.00 V / 1.200 A

Original publication on 2008-11-11, revision 1.5


This document is an engineering report describing a universal input, 5 V, 6 W outputFlyback power supply. This reference design is based on the LinkSwitch-CV family ofdevices and utilizes the LNK625PG.The document contains the power supply specification, schematic, bill of materials,transformer documentation, printed circuit layout, and performance data.The schematic in Figure 2 shows an adapter design using the LNK625PG that providesvery tight constant voltage (CV) performance. The circuit is designed to operate from90 VAC to 265 VAC input, with an output voltage of 5 V providing a maximum loadcurrent of 1.2 A. It consumes very little standby power and uses no Y-Capacitor to meetstringent EMI requirements. The adapter also meets and exceeds both CEC and EnergyStar 2.0 regulations.


  • Eliminates optocoupler and all secondary side control circuitry• EcoSmart® – Easily meets all existing and proposed international energy efficiencystandards – China (CECP) / EISA / Energy STAR / European Commission• ON/OFF control provides constant efficiency event at very light loads• No-load consumption <100 mW at 265 VAC• Meets ENERGY STAR 2.0 active mode efficiency• 76 % vs 70 % requirement at board• 73 % vs 70 % requirement at end of 6 ft, 315 mW output cable• Ultra-low leakage current: <5 μA at 265 VAC input (no Y capacitor required)• Over-temperature protection – tight tolerance (±5%) with hysteretic recovery for safePCB temperatures under all conditions• Auto-restart output short circuit and open-loop protection• Easy compliance to EN550022 and CISPR-22 Class B EMI standards• Green package: halogen free and RoHS compliant


  Order Code SPEC Product series Vin VOut1
(V (AC))
Montageart Samples
750811016 PDF MID-OLPI Offline Flyback Transformers for Power Integrations 85 - 265 V (AC) 5 1.2 13.5 100 1.67 16.42 : 1 : 2.71 450 4500 16.9 18.8 13 THT