XFX 1000W Pro Series 80 Plus Platinum

Internal Design and Components

Seasonic builds this particular power supply and uses the full bridge with a resonant circuit behind. The full bridge is composed of two half bridges (one high-side and one low-side MOSFET each) which work alternately so the transformer can be driven into a balanced state. This full bridge allows them to reduce the size of the main transformer and theoretically doubles the possible output power of the half bridge converter. This only applies when identical MOSFETs are used and if all other components are chosen correctly as well. As you can see the heatsinks on the secondary side are very thin, but the MOSFETs have a low power dissipation and get cooled by the conduction path and the fan as well. Those blue capacitors beside the heatsinks are made by Nippon Chemi-Con, as are all the others in this PSU.

The EMI filtering consists of a complete mains filter with two additional X capacitors, four Y capacitors, one more common mode choke, and one differential mode choke. Moreover inrush current gets limited by a thermistor, and a MOV as passive OVP is included as well. Both rectifier bridges get their own heatsink for cooling. In the power factor pre-regulator we find three large main caps and a serperate IC for PFC control on a single sided PCB. On the fifth picture in our gallery, two MOSFETs in a large TO-247 case can be seen. Their gate connectors are equipped with a ferrite bead. Besides this the PFC diode on the left has nearly no reverse recovery time.

The resonant circuit in the middle shows one important change. Two conductions of the IC CM6901 (on a small PCB) lead to a small inductor, which is located between the resonant capacitor, the resonant coil, and the small "auxiliary coil" to relieve the main transformer. With this the current can be measured in the resonant circuit to improve regulation. A second winding is connected to the main PCB and the magnetic flux in the core passes through the regulation winding.

The buck converters for +3.3V and +5V are located on the modular PCB. With the APW7159 controller XFX is able to switch at a high frequency. With this the size of passive components can be reduced again. +12V has many short transitions to the modular board, which means resistance is somewhat lower; this helps to increase efficiency a little. The protecion IC can be found on another seperate PCB on the left. As expected XFX has a native dual output design for +12V. Soldering quality is outstanding, as is usually the case with Seasonic built PSUs. We couldn't find any dry soldered joints, though a few parts did get a bit too much solder.