Corsair TX850 V2 Power Supply Review

Primary Analysis

On this page we will take an in-depth look at the primary stage of the Corsair TX850 V2. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses two GBU806 rectifying bridges connected in parallel, both attached to an individual heatsink. Each bridge supports up to 8 A at 100° C, so in theory, you would be able to pull up to 1,840 W from a 115 V 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 these particular components. The real limit will depend on all the components combined in this power supply. These are the same bridges used in the 750 W version.

Figure 10: Rectifying bridges

The active PFC circuit uses two SPP24N60C3 MOSFETs, which are capable of delivering up to 24.3 A at 25° C or up to 15.4 A at 100° C in continuous mode (note the difference temperature makes), or up to 72.9 A in pulse mode at 25° C, each. These transistors present a 160 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. It is interesting to note how, in order to improve thermal dissipation, the manufacturer added a metallic plate between these transistors and the aluminum heatsink (see Figure 11). These are the same transistors used in the 750 W model.

Figure 11: Active PFC transistors

This power supply uses two 330 µF x 400 V electrolytic capacitors to filter the output from the active PFC circuit; this is the equivalent of one 660 µF x 400 V capacitor. The Corsair TX750 V2 uses one 220 µF x 400 V and one 330 µF x 400 V capacitors connected in parallel. The capacitors are Japanese, from Rubycon, and labeled at 105° C.

In the switching section, another two SPP24N60C3 MOSFET transistors are used, installed in the two-transistor forward configuration. The specifications for these transistors were already published above. The 750 W model uses transistors with lower current limits (20.7 A at 25° C or 13.1 A at 100° C).

Figure 12: One of the switching transistors

The primary is controlled by a CM6802 active PFC/PWM combo controller.

Figure 13: Active PFC/PWM combo controller

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