On this page, we will take an in-depth look at the primary stage of the Kingwin Power Force 850 W. For a better understanding, please read our “Anatomy of Switching Power Supplies” tutorial.
This power supply uses two GBU805 rectifying bridges connected in parallel, which are attached to an individual heatsink. Each bridge supports up to 8 A at 100° C. In theory, you would be able to pull up to 1,840 W from a 115 V power grid. Assuming 80% efficiency, the bridges would allow this unit to deliver up to 1,472 W witho
ut burning themselves out. Of course, we are only talking about these particular components. The real limit will depend on all the components combined in this power supply.
The active PFC circuit uses two IPW60R070C6 MOSFETs, each one supporting up to 53 A at 25° C or 34 A at 100° C in continuous mode (note the difference temperature makes), or 159 A at 25° C in pulse mode. These transistors present a 70 mΩ maximum resistance when turned on, a characteristic called RDS(on). The lower the number the better, meaning that the transistor will waste less power, and the power supply will have a higher efficiency.
The output of the active PFC circuit is filtered by one 560 µF x 400 V Japanese electrolytic capacitor from Matsushita (Panasonic), labeled at 105° C.
In the switching section, two FMP20N60S1 MOSFETs are employed using the traditional two-transistor forward configuration. Each transistor supports up to 20 A at 25° C or 12.6 A at 100° C in continuous mode, or up to 60 A at 25° C in pulse mode, with a maximum RDS(on) of 190 mΩ.
The active PFC and the switching transistors are controlled by the famous CM6800 integrated circuit.
Let’s now take a look at the secondary of this power supply.