In Win Commander II 850 W Power Supply Review

Secondary Analysis

The In Win Commander II 850 W uses a synchronous rectification. In this design, the rectifying diodes are replaced with transistors in order to increase efficiency. On top of that, this power supply uses a DC-DC design, meaning that the +5 V and +3.3 V outputs are generated by two smaller switching power supplies that are connected to the main +12 V rail. So, this unit is basically a +12 V power supply. This is also done to increase efficiency.

The +12 V output uses five ME80N08A MOSFETs, each one supporting up to 80 A at 25° C in continuous mode or up to 300 A at 25° C in pulse mode, with a maximum RDS(on) of 8.7 mΩ, which is extremely low (i.e., higher efficiency). Unfortunately, the manufacturer doesn’t publish the current limits at 100° C. Three of these transistors are used for the direct rectification, and two for the “freewheeling” part of the rectification.

Figure 14: The +12 V transistors

This power supply has two DC-DC modules, one for converting +12 V into +5 V and the other for converting +12 V into +3.3 V. Each module is managed by an APW7073 PWM controller and uses four ME75N03 MOSFETs, each one supporting up to 86 A at 25° C or 70 A at 70° C in continuous mode, or up to 200 A at 25° C in pulse mode, with a maximum RDS(on) of only 9 mΩ.

Figure 15: One of the DC-DC modules

Figure 16: One of the DC-DC modules

This power supply uses a PS232S monitoring integrated circuit, which supports over voltage (OVP), under voltage (UVP), and over current (OCP) protections. This chip has six OCP channels, one for +3.3 V, one for +5 V, and four for +12 V, correctly matching the number of +12 V rails advertised by the power supply manufacturer (four).

Figure 17: Monitoring circuit

The electrolytic capacitors available in the secondary are from Teapo, and are labeled at 105° C.