3R System AK6-600M Power Supply Review

Primary Analysis

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

This power supply uses one U15K80R rectifying bridge, which isn’t attached to a heatsink. Unfortunately, we couldn’t find the exact datasheet for this bridge, but we can assume it is a 15 A component. (The real limit is lower, as this bridge isn’t attached to a heatsink.) 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. Of course, we are only talking about this particular component. The real limit will depend on all the components combined in this power supply. This is the same bridge used in the 500 W model.

Figure 9: Rectifying bridge

The active PFC circuit uses two SPP20N60C3 MOSFETs, each one supporting up to 20.7 A at 25° C or 13.1 A at 100° C in continuous mode (note the difference temperature makes), or 62.1 A at 25° C in pulse mode. These transistors present a 190 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. This is the same configuration used in the 500 W model.

The output of the active PFC circuit is filtered by one 330 µF x 400 V electrolytic capacitor from Asia’x, labeled at 105° C. The 500 W model uses a 270 µF x 400 V capacitor here.

In the switching section, another two SPP20N60C3 MOSFETs are employed using the traditional two-transistor forward configuration. The specifications for these transistors were already discussed above. This is the same configuration used in the 500 W model.

Figure 10: One of the active PFC transistors and the switching transistors

The primary is managed by a CM6802 active PFC/PWM combo controller.

Figure 11: Active PFC/PWM combo controller

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