Kingwin Lazer Platinum 850 W Power Supply Review

Primary Analysis

On this page we will take an in-depth look at the primary stage of the Kingwin Lazer Platinum 850 W. For a better understanding, please read our “Anatomy of Switching Power Supplies” tutorial.

This power supply uses two US30K80R rectifying bridges, which are attached to an individual heatsink. Each bridge supports up to 30 A at 97° C. In theory, you would be able to pull up to 6,900 W from a 115 V power grid. Assuming 80% efficiency, the bridges would allow this unit to deliver up to 5,520 W without burning themselves out (or 6,210 W with 90% efficiency). Of course, we are only talking about these particular components. The real limit will depend on all the components combined in this power supply. The “Gold” version of this power supply uses only one of these bridges.

Figure 10: Rectifying bridges

The active PFC circuit uses two IPW50R140CP MOSFETs, each one supporting up to 23 A at 25° C or 15 A at 100° C in continuous mode (note the difference temperature makes), or 56 A at 25° C in pulse mode. These transistors present a 140 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. Incredibly, the “Gold” version of this power supply uses transistors that are a little bit stronger (25 A at 25° C) here, with lower RDS(on) (125 mΩ).

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 two 390 µF x 400 V Japanese electrolytic capacitors, from Chemi-Con, labeled at 105° C and connected in parallel. This is the equivalent of one 780 µF x 400 V capacitor.

In the switching section, another two IPW50R140CP MOSFETs are employed using a resonant configuration. The specifications for these transistors were already discussed above.

Figure 12: The two active PFC transistors, the two active PFC diodes, and the two 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 13: Resonant controller

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