Corsair TX750W Power Supply Review

Secondary Analysis

This power supply uses four Schottky rectifiers on its secondary, the same models used on Thermaltake Toughpower 750W.

The +12 V output is produced by two STPS60L45CW Schottky rectifiers connected in parallel, which can deliver up to 60 A each (30 A per internal diode, measured at 135° C). The maximum theoretical current the +12 V line can deliver is given by the formula I / (1 – D), where D is the duty cycle used and I is the maximum current supported by the rectifying diode (which in this case is made by two 30 A diodes in parallel). Just as an exercise, we can assume a typical duty cycle of 30%. This would give us a maximum theoretical current of 86 A or 1,029 W for the +12 V output. The maximum current this line can really deliver will depend on other components, in particular the coil used. As you can see this section is highly overspec’ed.

The +5 V output is produced by one STPS40L45CW Schottky rectifier, supporting up to 40 A (20 A per internal diode, measured at 130° C). The maximum theoretical current the +5 V line can deliver is given by the formula I / (1 – D), where D is the duty cycle used and I is the maximum current supported by the rectifying diode (which in this case is made by one 20 A diode). Just as an exercise, we can assume a typical duty cycle of 30%. This would give us a maximum theoretical current of 29 A or 143 W for the +5 V output. The maximum current this line can really deliver will depend on ot
her components, in particular the coil used. As you can see this section is highly overspec’ed.

The +3.3 V output is also produced by another STPS40L45CW Schottky rectifier, supporting up to 40 A (20 A per internal diode, measured at 130° C). Using the same math this would equal 29 A or 94 W.

Even though this power supply has a separated rectifier for the +3.3 V output, this rectifier is connected to the same transformer output as the +5 V line, so the maximum current +5 V and +3.3 V can pull together is limited by the transformer.

Figure 13: The four Schottky rectifiers used on the secondary.

In Figure 14, you can see the thermal sensor used by this power supply, in charge of changing the fan speed according to the power supply internal temperature.

Figure 14: Thermal sensor.

This power supply uses only Japanese capacitors, all rated at 105° C. The active PFC capacitor is from Matushita (Panasonic) while the smaller ones are from Chemi-Con.