Corsair TX550M Power Supply Review

Secondary Analysis

The Corsair TX550M 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. This design improves efficiency.

The +12 V output uses five STPS3045CT Schottky rectifiers (30 A, 15 A per internal diode at 155° C, 0.84 V maximum voltage drop).

Figure 14: +12 V rectifiers

As explained, the +5 V and +3.3 V outputs are produced by two DC-DC converters, which are physically located on the modular cabling printed circuit board. They are controlled by an APW7159 integrated circuit, using eight AP72T03GH MOSFETs, four for each output. Each transistor supports up to 62 A at 25° C or 44 A at 100° C in continuous mode, up to 190 A at 25° C in pulse mode, and 9 mΩ RDS(on).

Figure 15: The DC-DC converters

Figure 16: The DC-DC converters

This power supply uses a WT7502 monitoring integrated circuit, which is a very simple chip, supporting only over voltage (OVP) and under voltage (UVP) protections. On the solder side of the printed circuit board shown in Figure 17, there is an LM393 voltage comparator, which we guess makes the missing protections.

Figure 17: 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, while the capacitors that filter the +5 V and +3.3 V outputs are solid. See Figure 15.