OCZ ModXStream Pro 600 W Power Supply Review

Primary Analysis

On this page we will take an in-depth look at the primary stage of OCZ ModXStream Pro 600 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses one GBU1005 rectifying bridge, which supports up to 10 A at 100° C if a heatsink is used, which is the case. 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 itself 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: Rectifying bridge.

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 and diode.

The electrolytic capacitor used to filter the output from the active PFC circuit is from Teapo and labeled at 85° C.

The reviewed power supply uses two STP25NM60N power MOSFET transistors on its switching section, installed on the traditional two-transistor forward configuration. Each transistor can handle up to 21 A at 25° C or up to 13 A at 100° C in continuous mode, or up to 84 A at 25° C in pulse mode, with a maximum RDS(on) of 160 mΩ.

Figure 11: Switching transistors.

The primary is controlled by a FAN4800 PFC/PWM combo controller.

Figure 12: PFC/PWM combo controller.

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