Fractal Design Integra R2 750 W Power Supply Review

Primary Analysis

On this page, we will take an in-depth look at the primary stage of the Fractal Design Integra R2 750 W. For a better understanding, please read our “Anatomy of Switching Power Supplies” tutorial.

This power supply uses one GBJ1506 rectifying bridge, attached to the same heatsink as the active PFC transistors. This component supports up to 15 A at 100° C, so in theory, you would be able to pull up to 1,725 W from a 115 V 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 this particular component. The real limit will depend on all the components combined in this power supply.   

Figure 11: Rectifying bridge

The active PFC circuit uses three IPP60R190C6 MOSFETs, each supporting up to 20.2 A at 25° C or 12.8 A at 100° C in continuous mode (note the difference temperature makes), or 59 A in pulse mode at 25° C. These transistors present a 190 mΩ 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.

Figure 12: Active PFC transistors and diode

The output of the active PFC circuit is filtered by one 470 µF x 400 V electrolytic capacitor, from Teapo, labeled at 105° C.

Figure 13: Capacitor

In the switching section, two IPP60R190E6 MOSFETs are used in the traditional two-transistor forward configuration. The specifications for these transistors are the same as for the active PFC transistors.   

Figure 14: One of the switching transistors

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

Figure 15: Active PFC/PWM combo controller

Let’s now take a look at the secondary of this power supply.