On this page we will take an in-depth look at the primary stage of Liberty ECO 500 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses one GBU10J rectifying bridge in its primary, which support up to 10 A at 100º C. This component is clearly overspec'ed: at 115 V this unit would be able to pull up to 1,150 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 920 W without burning this component. Of course we are only talking about this component and the real limit will depend on all other components from the power supply.

click to enlarge
Figure 10: Rectifying bridge.

For the active PFC circuit Liberty ECO 500 W uses two 2SK2698 power MOSFET transistors, which one capable of delivering up to 15 A in continuous mode  or up to 60 A in pulse mode, both values rated at 25º C.

The active PFC capacitor is Japanese from Hitachi and rated at 85º C.

In the switching section, another two 2SK2698 power MOSFETs are used on the traditional two-transistor forward configuration. The specs for these transistors you can read above.

click to enlarge
Figure 11: Two of the four power MOSFET transistors used on the primary.

The primary is controlled by a CM6802 PWM/PFC controller combo, which is a new version of the famous CM6800 that consumes less power.

click to enlarge
Figure 12: PWM/PFC controller.

Now let’s analyze the secondary section from Liberty ECO 500 W.