Corsair GS500 Power Supply Review

Primary Analysis

On this page we will take an in-depth look at the primary stage of the Corsair GS500. For a better understanding, please read our “Anatomy of Switching Power Supplies” tutorial.

This power supply uses one GBU1006 rectifying bridge, which is attached to a heatsink that is connected to the heatsink of the active PFC transistors. This bridge supports up to 10 A at 100° C. So, in theory, you would be able to pull up to 1,150 W from a 115 V 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 particular component. The real limit will depend on all the components combined in this power supply.

Figure 10: Rectifying bridge

The active PFC circuit uses two MDF18N50 MOSFETs, each supporting up to 18 A at 25° C or 11 A at 100° C in continuous mode (see the difference temperature makes) or 72 A at 25° C in pulse mode. These transistors present a maximum 270 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 11: Active PFC transistors and diode

The output of the active PFC circuit is filtered by one 330 µF x 400 V electrolytic capacitor, from Samxon, labeled at 85° C.

In the switching section, another two TK13A50DA MOSFETs are employed using the traditional two-transistor forward configuration. Each transistor supports up to 12.5 A at 25° C in continuous mode or up to 50 A at 25° in pulse mode, with a maximum RDS(on) of 470 mΩ. Unfortunately, the manufacturer for these transistors doesn’t publish the current limits at 100° C.

Figure 12: Switching transistors

The primary is managed by the famous CM6800 active PFC/PWM combo controller.

Figure 13: Active PFC/PWM combo controller

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