OCZ Fatal1ty 750 W Power Supply Review

Primary Analysis

On this page we will take an in-depth look at the primary stage of OCZ Fatal1ty 750 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses one TS15P05G rectifying bridge in its primary, supports up to 15 A at 110° C, if a heatsink is used. This component is installed on the same heatsink as the active PFC transistors. In theory you would be able to pull up to 1,725 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 1,380 W without burning itself out. Of course, we are only talking about these components, and the real limit will depend on all the other components in this power supply.

Figure 9: Rectifying bridge.

The active PFC circuit uses two FCA20N60 power MOSFET transistors, each one capable of delivering up to 20 A at 25° C or 12.5 A at 100° C in continuous mode (note the difference temperature makes) or 60 A in pulse mode at 25° C. These transistors present a 150 mΩ resistance when turned on, a characteristic called RDS(on). The lower this number the better, meaning that the transistors will waste less power and the power supply will achieve a higher efficiency.

Figure 10: Active PFC transistors.

The electrolytic capacitor used to filter the output of the active PFC circuit is Japanese from Chemi-Con and labeled at 105° C. This is the best possible configuration.

In the switching section, another two FCA20N60 power MOSFET transistors are used. The specifications for these transistors were already published above.

Figure 11: Switching transistors.

The primary is controlled by the omnipresent CM6800 PFC/PWM combo controller.

Figure 12: Active PFC/PWM combo controller.

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