PC Power & Cooling Silencer Mk II 650 W Power Supply Review

Primary Analysis

On this page we will take an in-depth look at the primary stage of the PC Power & Cooling Silencer Mk II 650 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses one GBJ2506 rectifying bridge on its primary, but unfortunately it isn’t attached to a heatsink. This component supports up to 25 A at 100° 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. Of course, we are only talking about this component, and the real l
imit will depend on all the other components in this power supply. The 750 W model uses two 15 A bridges connected in parallel here.

Figure 9: Rectifying bridge

The active PFC circuit uses two SPW20N60C3 MOSFETs, each one capable of delivering up to 20.7 A at 25° C or up to 13.1 A at 100° C (note the difference temperature makes) in continuous mode, or up to 62.1 A in pulse mode at 25° C. These transistors present a 190 mΩ resistance when turned on, a characteristic called RDS(on). The lower this number the better, meaning that the transistors will waste less power and the power supply will have a higher efficiency. The 750 W model uses more powerful transistors here.

Figure 10: Active PFC transistors

This power supply uses two electrolytic capacitors to filter the output from the active PFC circuit. The use of more than one capacitor here has absolute nothing to do with the “quality” of the power supply, as laypersons may assume (including people without the proper background in electronics doing power supply reviews around the web). Instead of using one big capacitor manufacturers may choose to use two or more smaller components that will give the same total capacitance, in order to better accommodate space on the printed circuit board, as two capacitors with the same total capacitance are physically smaller than a single capacitor with equivalent capacitance. The Silencer Mk II 650 W uses two 330 µF x 400 V capacitors connected in parallel, the equivalent of one 660 µF x 400 V capacitor. They are manufactured by Rubycon, a Japanese company, and labeled at 105° C.

In the switching section, two IPP60R190C6 power MOSFETs are used in the traditional two-transistor forward configuration. They are capable of handling up to 20.2 A at 25° C or up to 12.8 A at 100° C in continuous mode, or up to 59 A at 25° C in pulse mode, with an RDS(on) of 190 mΩ. The 750 W model uses more powerful transistors here.

Figure 11: Active PFC diode and one of the switching transistors

The primary is controlled by the omnipresent CM6800 active PFC/PWM combo.

Figure 12: Active PFC/PWM combo controller

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