In Win Commander II 850 W Power Supply Review

Primary Analysis

On this page we will take an in-depth look at the primary stage of the In Win Commander II 850 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses two BU1006A rectifying bridges connected in parallel on its primary, which are attached to the same heatsink where the active PFC transistors are located. These components support up to 10 A at 90° C each, so in theory, you would be able to pull up to 2,300 W from a 115 V 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 particular components. The real limit will depend on all the components combined in this power supply.

Figure 10: Rectifying bridges

The active PFC circuit uses two SPW24N60C3 MOSFETs, each supporting up to 24.3 A at 25° C or 15.4 A at 100° C in continuous mode (note the difference temperature makes), or 72.9 A in pulse mode at 25° C. These transistors present a 160 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.

Figure 11: Active PFC transistors

This power supply uses two electrolytic capacitors connected in parallel to filter the output of the active PFC circuit. Each capacitor is a 390 µF x 400 V model, which is equivalent to a single 780 µF x 400 V capacitor. These capacitors are Japanese, from Matsushita (Panasonic), and labeled at 105° C.

In the switching section, another two SPW24N60C3 MOSFETs are used, installed in the traditional two-transistor forward configuration. The specifications for these transistors were already discussed above.

Figure 12: Switching transistors

The primary is managed 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.