Primary Analysis
Contents
On this page we will take an in-depth look at the primary stage of the Enermax Platimax 600 W. For a better understanding, please read our “Anatomy of Switching Power Supplies” tutorial.
This power supply uses one LL25XB60 rectifying bridge, which is attached to an individual heatsink. This bridge supports up to 25 A at 113° C, so in theory, you would be able to pull up to 2,875 W from a 115 V power grid. Assuming 80% efficiency, the bridge would allow this unit to deliver up to 2,300 W without burning itself out (or 2,587.5 W at 90% efficiency). Of course, we are only talking about this particular component. The real limit wil
l depend on all the components combined in this power supply.
Figure 10: Rectifying bridge
The active PFC circuit uses two SiHG22N60S MOSFETs, each one supporting up to 22 A at 25° C or 13 A at 100° C in continuous mode (note the difference temperature makes), or 65 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.
Figure 11: The active PFC transistors and diode
The active PFC is managed by a CM6502S active PFC controller.
Figure 12: Active PFC controller
The output of the active PFC circuit is filtered by a 470 μF x 400 V Japanese electrolytic capacitor, from Matsushita (Panasonic), labeled at 105° C.
In the switching section, another two SiHG22N60S MOSFETs are employed using a resonant configuration. The specifications for these transistors were already discussed above.
Figure 13: The switching transistors
The switching transistors are controlled by a CM6901 resonant controller.
Figure 14: Resonant controller
Let’s now take a look at the secondary of this power supply.
