Primary Analysis

On this page, we will take an in-depth look at the primary stage of the Fractal Design Tesla R2 650 W. For a better understanding, please read our “Anatomy of Switching Power Supplies” tutorial.

This power supply uses one US15KB80R rectifying bridge, attached to the same heatsink as the active PFC transistors. This component supports up to 15 A at 101° 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 (or 1,553 W at 90% efficiency). Of course, we are only talking about this particular component. The real limit will depend on all the components combined in this power supply.

Fractal Design Tesla R2 650wFigure 11: Rectifying bridge

The active PFC circuit uses one IPW50R140CP MOSFET, which supports up to 23 A at 25° C or 15 A at 100° C in continuous mode (note the difference temperature makes), or 56 A in pulse mode at 25° C. This transistor presents a 140 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. The Rosewill FORTRESS-650 uses a transistor, an IPW60R99C6, with higher current limit and lower RDS(on).

The active PFC circuit is controlled by a CM6502 integrated circuit.

Fractal Design Tesla R2 650wFigure 12: Active PFC controller

The output of the active PFC circuit is filtered by one 390 µF x 400 V electrolytic capacitor, from Teapo, labeled at 105° C. The Rosewill FORTRESS-650 uses a Japanse capacitor here.

Fractal Design Tesla R2 650wFigure 13: Capacitor

In the switching section, two IPW60R190C6 MOSFETs are used in a resonant configuration. Each transistor supports up to 20.2 A at 25° C or 12.8 A at 100° C in continuous mode, or 59 A in pulse mode at 25° C, with a maximum RDS(on) of 190 mΩ. The Rosewill FORTRESS-650 uses two IPW50R140CP transistors here. (The specifications for these transistors were already discussed above.)

Fractal Design Tesla R2 650wFigure 14: One of the switching transistors, the active PFC diode, and the active PFC transistor

The switching transistors are controlled by a CM6901 integrated circuit.  

Fractal Design Tesla R2 650wFigure 15: Resonant controller

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

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.