PC Power & Cooling Silencer 750 Quad Power Supply Review

Primary Analysis

On this page we will take an in-depth look at the primary stage of PC Power & Cooling Silencer 750 Quad. For a better understanding, please read
our Anatomy of Switching Power Supplies tutorial.

This power supply uses one GBJ1506 rectifying bridge in its primary, which can deliver up to 15 A (rated at 100° C). As you can see in Figure 9 this bridge is attached to a heatsink. This component is clearly overspec’ed: at 115 V this unit would be able to pull up to 1,725 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 1,380 W without burning this component. Of course we are only talking about this component and the real limit will depend on all other components from the power supply.

Figure 9: Rectifying bridge.

The active PFC circuit uses two SPW35N60C3 power MOSFET transistors, each one capable of handling up to 21.9 A in continuous mode at 100° C (or 34.6 A at 25° C; see the difference temperature makes) or 103.8 A in pulse mode at 25° C. These transistors are located on the same heatsink as the switching transistors.

On the switching section this power supply uses two SPP24N60C3 power MOSFET transistors in the traditional two-transistor forward configuration. Each transistor is capable of handling up to 15.4 A at 100° C in continuous mode (or 24.3 A at 25° C) or up to 72.9 A in pulse mode at 25° C.

Figure 10: Active PFC transistors (left), active PFC diode and switching transistors (right).

The primary section of this power supply is controlled by a UCC28515DW integrated circuit, which is a PFC/PWM controller combo.  This integrated circuit is located on a small printed circuit board attached to the main printed circuit board.

Figure 11: Active PFC/PWM controller combo.