SHARE

## Primary Analysis

On this page we will take an in-depth look at the primary stage of Cooler Master eXtreme Power Plus 550 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses two GBU1006 rectifying bridges connected in parallel, each one supporting up to 10 A at 100° C. At 115 V this unit would be able to pull up to 2,300 W from the power grid; assuming 80% efficiency, the bridges would allow this unit to deliver up to 1,840 W without burning themselves out. Of course, we are only talking about these components, and the real limit will depend on all the other components in this power supply. It is always nice to see a huge overspecification like this one.

Figure 9: Rectifying bridges.

This unit is based on a single-transistor forward topology, which is good to see, since usually low-end units are based on the obsolete half-bridge design. Two 2SK2611 power MOSFETs are connected in parallel on the switching section in order to double the maximum current this section can handle. Each transistor supports up to 9 A at 25° C in continuous mode, or up to 27 A at 25° C in pulse mode, so the switching section can deliver up to 18 A at 25° C. Unfortunately the manufacturer does not provide the current limits at 100° C. These transistors present an RDS(on) of 1.1 Ω, which is insanely high (low efficiency). This number measures the resistance provided by the transistors when they are turned on; the lower this number, the better (higher efficiency). These are the same transistors used on eXtreme Power Plus 500 W, even though this other model is manufactured by a different company.

Figure 10: One of the switching transistors.

The switching transistors are controlled by a TL3842 PWM controller, which is located on the primary.

Figure 11: PWM controller.

The two electrolytic capacitors from the voltage doubler are from Su’scon and labeled at 85° C.

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

## Contents

Gabriel Torres is a Brazilian best-selling ICT expert, with 24 books published. He started his online career in 1996, when he launched Clube do Hardware, which is one of the oldest and largest websites about technology in Brazil. He created Hardware Secrets in 1999 to expand his knowledge outside his home country.