EPR-54 – LinkSwitch 2.75 W Low Cost Charger / Adapter
07-May-2004
1 Introduction
This document is an engineering report describing a 5.5 V, 500 mA charger/adapter
power supply. The power supply utilizes the LinkSwitch LNK520 device, optimized for
bias winding feedback. The LinkSwitch integrates a 700 V MOSFET, PWM controller,
start-up, thermal shut-down, and fault protection circuitry. This power supply is a cost
effective replacement of linear transformer based power supplies with the additional
features of universal input range and high energy efficiency.
Compared to the LNK500, the optimized switching characteristics of the LNK520 and the
low-side configuration provides improved EMI performance and less variation in EMI
performance from design to design.
The document contains the power supply specification, schematic, bill of materials,
transformer documentation, printed circuit layout, and performance data.
Figure 1 – Populated Circuit Board Photograph.
An alternate design utilizing simplified EE16 transformer construction is presented. See
Appendix A for schematic, construction details and performance curves.
Power Integrations
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