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Secondary Analysis

As one would expect in a high-efficiency power supply, the Fractal Design Tesla R2 650 W uses a synchronous design, where the Schottky rectifiers are replaced with MOSFETs. Also, the reviewed product uses a DC-DC design in its secondary. This means that the power supply is basically a +12 V unit, with the +5 V and +3.3 V outputs produced by two smaller power supplies connected to the main +12 V rail. Both designs are used to increase efficiency.

The +12 V output uses four IPP041N04N MOSFETs, each one supporting up to 80 A at 100° C in continuous mode, or up to 400 A at 25° C in pulse mode, with a maximum RDS(on) of 4.1 mΩ. The Rosewill FORTRESS-650 uses four IPP023N04N G, which provide higher current limits and a lower RDS(on).

Fractal Design Tesla R2 650wFigure 16: The +12 V transistors

As explained, the +5 V and +3.3 V outputs are produced by two DC-DC converters, located on a daughterboard soldered to the main printed circuit board. Each converter is controlled by a CAT7523 integrated circuit and uses a pair of IPD031N03L MOSFETs, each supporting up to 90 A at 100° C in continuous mode and up to 400 A at 25° C in pulse mode, with a maximum RDS(on) of 3.1 mΩ.

Fractal Design Tesla R2 650wFigure 17: The DC-DC converters

Fractal Design Tesla R2 650wFigure 18: The DC-DC converters

The outputs of the power supply are monitored by a GR8313 integrated circuit, which only supports over voltage (OVP) and under voltage (UVP) protections. 

Fractal Design Tesla R2 650wFigure 19: Monitoring circuit

This power supply uses a mix of solid and electrolytic capacitors in its secondary. The electrolytic capacitors are from Teapo and labeled at 105° C, as usual. The solid capacitors are from CapXon. The Rosewill FORTRESS-650 uses Japanese capacitors here.

Fractal Design Tesla R2 650wFigure 20: Capacitors

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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.