On this page we will take an in-depth look at the primary stage of Thermaltake Toughpower XT 775 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses two GBU806 rectifying bridges connected in parallel in its primary. Each one supports up to 8 A at 100º C if a heatsink is used, which is the case (without a heatsink the limit drops to 3.5 A also at 100º C). So in theory you would be able to pull up to 1,840 W from the power grid; assuming 80% efficiency, the bridges would allow this unit to deliver up to 1,472 W without burning themselves. Of course we are only talking about this component and the real limit will depend on all other components from the power supply.

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Figure 9: One of the rectifying bridges.

Two SPW20N60C3 power MOSFETs are used on the active PFC circuit, each one capable of delivering up to 20.7 A at 25º C or 13.1 A at 100º C in continuous mode (note the difference temperature makes) or up to 62.1 A at 25º C in pulse mode. These transistors present a maximum resistance of 190 mΩ when turned on, a characteristic called RDS(on). This number indicates the amount of power that is wasted, so the lower this number the better, as less power will be wasted thus increasing efficiency.

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Figure 10: Active PFC transistors.

The electrolytic capacitor in charge of filtering the output from the active PFC circuit is Japanese from Chemi-Con and rated at 85º C.

In the switching section, two IRFP460A power MOSFET transistors are used in the traditional two-transistor forward configuration, each one capable of delivering up to 20 A at 25º C or up to 13 A at 100º C in continuous mode, or up to 80 A at 25º C in pulse mode, presenting an RDS(on) of 270 mΩ.

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Figure 11: Switching transistors.

This power supply uses the omnipresent CM6800 active PFC/PWM combo controller.

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Figure 12: Active PFC/PWM combo controller.

Now let’s take a look at the secondary of this power supply.