Thermaltake Toughpower XT 775 W Power Supply Review

Primary Analysis

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 100° C if a heatsink is used, which is the case (without a heatsink the limit drops to 3.5 A also at 100° 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 out. Of course we are only talking about this component and the real limit will depend on all other components from the power supply.

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 25° C or 13.1 A at 100° C in continuous mode (note the difference temperature makes) or up to 62.1 A at 25° 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.

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 85° 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 25° C or up to 13 A at 100° C in continuous mode, or up to 80 A at 25° C in pulse mode, presenting an RDS(on) of 270 mΩ.

Figure 11: Switching transistors.

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

Figure 12: Active PFC/PWM combo controller.

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