AZZA Platinum 750 W Power Supply Review

Primary Analysis

On this page we will take an in-depth look at the primary stage of the AZZA Platinum 750 W. For a better understanding, please read our “Anatomy of Switching Power Supplies&rdq
uo; tutorial.

This power supply uses one US30K80R rectifying bridge, which is attached, at the same time, to an individual heatsink and to the heatsink where the active PFC and switching transistors are attached. This bridge supports up to 30 A at 97° C. In theory, you would be able to pull up to 3,450 W from a 115 V power grid. Assuming 80% efficiency, the bridge would allow this unit to deliver up to 2,760 W without burning itself out (or 3,105 W at 90% efficiency). 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 IPP50R199CP MOSFETs, each one supporting up to 17 A at 25° C or 11 A at 100° C in continuous mode (note the difference temperature makes), or 40 A at 25° C in pulse mode. These transistors present a 199 mΩ maximum 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.

The active PFC circuit is managed by an NCP1653A active PFC controller. 

Figure 11: Active PFC controller

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.

Figure 12: Capacitor

In the switching section, two IPW50R140CP MOSFETs are employed using a resonant configuration. Each transistor supports up to 23 A at 25° C or 15 A at 100° C in continuous mode, or 56 A at 25° C in pulse mode, with a maximum RDS(on) of 140 mΩ. 

Figure 13: The two active PFC transistors, the active PFC diode, and one of the switching transistors

The switching transistors are controlled by an SF29601 controller, and we couldn’t find more information about this chip. We believe that the original manufacturer got a resonant controller and relabeled it, as SF stands for “Super Flower.” Interestingly enough, the controller is placed in the secondary of the power supply.

Figure 14: Resonant controller

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