Rosewill FORTRESS-650 Power Supply Review

Primary Analysis

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

This power supply uses one U15K80R rectifying bridge, which is attached to the same heatsink as the active PFC and switch transistors. Unfortunately, we couldn’t find the datasheet for this component, but we know it supports up to 15 A. 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 cour
se, we are only talking about this particular component. The real limit will depend on all the components combined in this power supply.

Figure 11: Rectifying bridge

The active PFC circuit uses an IPW60R099C6 MOSFET, which supports up to 37.9 A at 25° C or 24 A at 100° C in continuous mode (see the difference temperature makes) or 112 A at 25° C in pulse mode. This transistor presents a maximum 99 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 active PFC circuit is controlled by a CM6502S integrated circuit.

Figure 12: Active PFC controller

The output of the active PFC circuit is filtered by one 390 µF x 400 V Japanese electrolytic capacitor, from Chemi-Con, labeled at 105° C.

Figure 13:  Capacitor

In the switching section, two IPW50R140CP MOSFETs are employed using a resonant configuration. Each of these transistors supports up to 23 A at 25° C or 15 A at 100° C in continuous mode or up to 56 A at 25° C in pulse mode, with a maximum RDS(on) of 140 mΩ.

Figure 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.

Figure 15: Resonant controller

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