Corsair VX450W Power Supply Review

Secondary Analysis

This power supply uses four Schottky rectifiers on its secondary.

The +12 V output is produced by two SBR30A50CT Schottky rectifiers connected in parallel, which can deliver up to 30 A each (15 A per internal diode, measured at 110° 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 15 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 43 A or 514 W for the +12 V output. The maximum current this line can really deliver will depend on other components, in particular the coil used.

The +5 V output is produced by one STPS30L30CT Schottky rectifier, which support up to 30 A (15 A per internal diode, measured at 140° 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 15 A diode). Just as an exercise, we can assume a typical duty cycle of 30%. This would give us a maximum theoretical current of 21 A or 107 W for the +5 V output. The maximum current this line can really deliver will depend on other components, in particular the coil used.

The +3.3 V output is produced by another STPS30L30CT Schottky rectifier, which support up to 30 A (15 A per internal diode, measured at 140° C). So the maximum theoretical power the +3.3 V output can deliver is of 71 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 11: Three of the four Schottky rectifiers used on the secondary. The other rectifier is on the other side of the heatsink.

This power supply uses a semiconductor thermal sensor, which is very small and installed on the solder side of the printed circuit board, between the transformer and the +12 V rectifiers. This sensor is used to control the fan speed according to the power supply internal temperature.

Figure 12: Thermal sensor.

The secondary is monitored by a HY510N integrated circuit, which is installed on a small daughterboard and provides some of the power supply protections, like under voltage (UVP) and over voltage (OVP).

Figure 13: Monitoring integrated circuit.

This power supply only uses Japanese electrolytic capacitors from Chemi-Con, with the active PFC capacitor being rated at 105° C instead of 85° C like on other power supplies. This gives us a hint of the quality of this power supply. Antec EarthWatts 500 W, which is basically the same power supply with a different housing, uses Taiwanese caps.