On this page we will take an in-depth look at the primary stage of the Sentey Golden Steel Power 850 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.
This power supply uses one US30KB80R rectifying bridge, attached to the same heatsink used by the active PFC and switching transistors. This bridge supports up to 30 A at 97° C so, 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. Of course, we are only talking about these components. The real limit will depend on all the other components of this power supply.
The active PFC circuit uses two IPI60R125CP MOSFETs, each one capable of delivering up to 25 A at 25° C or up to 16 A at 100° C in continuous mode (note the difference temperature makes), or up to 82 A at 25° C in pulse mode. These transistors present a 125 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.
This power supply uses two electrolytic capacitors to filter the output from the active PFC circuit. The Sentey Golden Steel Power 850 W uses two 390 µF x 400 V capacitors connected in parallel, the equivalent of one 780 µF x 400 V capacitor. They are Japanese, manufactured by Chemi-Con, and labeled at 105° C.
Instead of using a PWM/PFC combo controller, this power supply uses two separate circuits, and the active PFC circuit is controlled by an NCP1653A integrated circuit.
In the switching section, another two IPI60R125CP MOSFET transistors are used. The specifications for these transistors are already published above.
Power supplies from the Sentey Golden Steel Power series use an LLC resonant switching design. The switching transistors are controlled by an SF29601 controller, but 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.
Let’s now take a look at the secondary of this power supply.