Primary Analysis
Contents
On this page we will take an in-depth look at the primary stage of the PC Power & Cooling Silencer Mk III 600 W. For a better understanding, please read our “Anatomy of Switching Power Supplies” tutorial.
This power supply uses one GBU1006 rectifying bridge, which is attached to an individual heatsink. This bridge supports up to 10 A at 100° C, so in theory, you would be able to pull up to 1,150 W from a 115
V power grid. Assuming 80% efficiency, the bridge would allow this unit to deliver up to 920 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.
Figure 10: 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 is, the better, meaning that the transistor will waste less power, and the power supply will have a higher efficiency.
Figure 11: One of the switching transistors, the active PFC diode, and the active PFC transistors
The output of the active PFC circuit is filtered by a 560 µF x 400 V Japanese electrolytic capacitor, from Chemi-Con, labeled at 105° C.
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.
The primary is controlled by an ICE1CS02 PWM/active PFC combo controller.
Figure 12: Active PFC/PWM controller
Let’s now take a look at the secondary of this power supply.
