Enermax Platimax 850 W Power Supply Review

Secondary Analysis

As one would expect in a high-efficiency power supply, the Enermax Platimax 850 W uses a synchronous design, where the Schottky rectifiers are replaced with MOSFETs. Also, the reviewed product uses a DC-DC design in its secondary. This means that the power supply is basically a +12 V unit, with the +5 V and +3.3 V outputs produced by two smaller power supplies connected to the main +12 V rail. Both designs are used to increase efficiency.

The +12 V output uses six IPP015N04N G MOSFETs, each one supporting up to 120 A at 100° C in continuous mode, or 400 A at 25° C in pulse mode, with an RDS(on) of only 1.5 mΩ. The 600 W model uses four 80 A transistors here.

Figure 15: +12 V transistors

As explained, the +5 V and +3.3 V outputs are produced by two DC-DC converters. Each is located on two small daughterboards soldered to the main printed circuit board. In Figures 16 and 17, you can see the physical aspect of one of these converters. They are controlled by an APW7073 integrated circuit, using three APM2556NU MOSFETs, each supporting up to 160 A at 25° C or 90 A at 100° C in continuous mode, up to 60 A at 25° C or 48 A at 100° C in pulse mode, and 7.5 mΩ RDS(on). These converters are identical to the ones used in the 600 W model.

Figure 16: One of the DC-DC converters

Figure 17: One of the DC-DC converters

This power supply uses a PS232S monitoring integrated circuit, which supports over voltage (OVP), under voltage (UVP), and over current (OCP) protections, with four +12 V channels, correctly matching the number of +12 V rails announced by the manufacturer.

Figure 18: Monitoring circuit

The electrolytic capacitors that filter the +12 V output are also Japanese, from Chemi-Con, and are labeled at 105° C, as usual. Some solid capacitors are also used.