PC Power & Cooling Silencer Mk II 750 W Power Supply Review

Secondary Analysis

This power supply uses a synchronous design in its secondary, meaning that the Schottky rectifiers were replaced by MOSFET transistors in order to increase efficiency. On top of that this unit uses a DC-DC project, meaning that this unit is basically a +12 V power supply, with the +5 V and +3.3 V outputs being generated by two small power supplies attached to the +12 V output.

The +12 V output is generated by three AOT480 MOSFETs, each one capable of handling up to 180 A at 25° C or up to 134 A at 100° C in continuous mode, or up to 500 A at 25° C in pulse mode, with an RDS(on) of only 4.5 mΩ.

Figure 14: +12 V transistors.

The +5 V and the +3.3 V outputs are generated by two small power supplies available on small daughterboards attached to the +12 V rail. Each of these power supplies is comprised of four IPD060N03L MOSFETs (50 A at 100° C, 6 mΩ resistance) and one APW7073 PWM controller.

Figure 15: One of the DC-DC converters.

This power supply uses a PS224 monitoring integrated circuit, which supports over voltage (OVP), under voltage (UVP) and over current (OCP) protections. The over current protection circuit available in this integrated circuit has four channels, one for +3.3 V, one for +5 V, and two for +12 V. However, in this power supply only one +12 V OCP channel is used, as it has a single-rail design.

Figure 16: Monitoring circuit.

Electrolytic capacitors from the secondary are also Japanese, from Chemi-Con, and labeled at 105° C.

One curious thing we noticed was the adaptation the manufacturer did to add an extra electrolytic capacitor to the +12 V rail (see in Figure 17).

Figure 17: Additional electrolytic capacitor for the +12 V rail.