Amacrox Free Earth 85PLUS 650 W Power Supply Review

Primary Analysis

On this page we will take an in-depth look at the primary stage of Amacrox Free Earth 85PLUS 650 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses two GBU606 rectifying bridges connected in parallel in its primary, each one being able to deliver up to 6 A at 100° C if a heatsink is used (which is the case) or up to 2.8 A at 100° C is a heatsink is not used. So in theory you would be able to pull up to 1,380 W from the power grid; assuming 80% efficiency, these bridges would allow this unit to deliver up to 1,104 W without burning themselves out. Talk about overspecification! Of course, we are only talking about these
components, and the real limit will depend on all the other components in this power supply. These are the same components used on Free Style 85PLUS 650 W.

Figure 9: Rectifying bridges.

Two FCPF21N60 power MOSFETs are used on the active PFC circuit, each one capable of delivering up to 20 A at 25° C or 12.5 A at 100° C in continuous mode (note the difference temperature makes) or up to 60 A at 25° C in pulse mode. These transistors present a maximum resistance of 150 mΩ when turned on, a characteristic called RDS(on). This number indicates the amount of power that is wasted, so the lower this number the better, as less power will be wasted thus increasing efficiency. These are the same components used on Free Style 85PLUS 650 W.

Figure 10: Active PFC transistors and diode.

The electrolytic capacitor is charge of filtering the active PFC output is Japanese from Hitachi and labeled at 105° C, which is great. This is the same component used on Free Style 85PLUS 650 W.

In the switching section, two SPA20N60C3 power MOSFET transistors are used, each one capable of delivering up to 20.7 A at 25° C or 13.1 A at 100° C in continuous mode, or up to 62.1 A in pulse mode at 25° C, with an RDS(on) of 190 mΩ. These are the same components used on Free Style 85PLUS 650 W.

Figure 11: Switching transistors.

This power supply uses the omnipresent CM6800 PFC/PWM combo controller.

Figure 12: PFC/PWM controller.

So far Free Earth 85PLUS 650 W is identical to Free Style 85PLUS 650 W. Let’s see if anything changed on the secondary.