Corsair TX550M Power Supply Review

Primary Analysis

On this page we will take an in-depth look at the primary stage of the Corsair TX550M. 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 an individual heatsink. 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% effi
ciency, 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 only one transistor, an IPW60R190E6, which supports 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 at 25° C in pulse mode. 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. Notice in Figure 11 how the manufacturer added a metal plate between the transistor and its heatsink in order to improve thermal dissipation.

Figure 11: The active PFC transistor

The output of the active PFC circuit is filtered by a Japanese capacitor, from Chemi-Con, labeled at 105° C.

In the switching section, two MDF18N50 MOSFETs are used in the traditional two-transistor forward configuration. Each of these transistors supports up to 18 A at 25° C or 11 A at 100° C in continuous mode (note the difference temperature makes), or 72 A at 25° C in pulse mode, with a 220 mΩ RDS(on).

Figure 12: The switching transistors

The primary is controlled by the omnipresent 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.