Corsair HX620W Power Supply Review

Secondary Analysis

This power supply uses four Schottky rectifiers on its secondary. 

The +12 V output is produced by two STPS6045CW Schottky rectifiers connected in parallel, which can deliver up to 60 A each (30 A per internal diode, measured at 130° 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 the rectifiers are highly overspec’ed.

The +5 V output is produced by one STPS60L30CW Schottky rectifier, also supporting up to 60 A (30 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 30 A diode). Just as an exercise, we ca
n assume a typical duty cycle of 30%. This would give us a maximum theoretical current of 43 A or 214 W for the +5 V output. The maximum current this line can really deliver will depend on other components, in particular the coil used.

And the +3.3 V output is produced by one STPS30L30CT Schottky rectifier, supporting up to 30 A (15 A per internal diode, measured at 140° C). Using the same math this would equal 21 A or 71 W. As mentioned, the maximum current this line can really deliver will depend on other factors.

Even though the +5 V line and the +3.3 V line have separated rectifiers, they share the same transformer output. So the maximum current both lines can deliver will depend a lot on the transformer.

On Figures 15 and 16 you can see the four power Schottky rectifiers used on the secondary section of this power supply and a 7805 voltage regulator which is probably used to simulate a load and allow the power supply to turn on.

Figure 15: Power rectifiers used on the secondary.

Figure 16: Power rectifiers used on the secondary.

This power supply uses a semiconductor thermal sensor, which is very small and installed on the solder side of the printed circuit board, right below the transformer ground outputs. This sensor is used to control the fan speed according to the power supply internal temperature.

Figure 17: Thermal sensor.

On this power supply all electrolytic capacitors are rated at 105° C and the capacitors from the secondary are Japanese, from Chemi-Con.