Corsair CX400W Power Supply Review

Secondary Analysis

This power supply uses four Schottky rectifiers on its secondary. The secondary from Corsair CX400W is absolutely identical to the secondary from Corsair VX450W, Antec EarthWatts 500 W and Arctic Cooling Fusion 550RF. So the main difference between Corsair CX400W and these other power supplies are the transistors used on the primary.

The maximum theoretical current each 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. Just as an exercise, we can assume a typical duty cycle of 30%.

The +12 V output is produced by two SBR30A50CT (30 A, 15 A per internal diode at 110° C, maximum voltage drop of 0.55 V) connected in parallel. This gives us a maximum theoretical current of 43 A or 514 W for the +12 V output.

By the way, we are now talking about the voltage drop presented by the rectifiers. This parameter shows how much voltage is wasted by the rectifier. The lower this number is, the better, as less voltage is wasted, increasing efficiency.

The +5 V output is produced by one STPS30L30CT Schottky rectifier (30 A, 15 A per internal diode at 140° C, maximum voltage drop of 0.57 V), giving us a maximum theoretical current of 21 A or 107 W for this output.

The +3.3 V output is produced by another STPS30L30CT Schottky rectifier, giving us a maximum theoretical current of 21 A or 71 W for this output.

All these numbers are theoretical. The real amount of current/power each output can deliver is limited by other components, especially by the coils used on each output.

Figure 12: Rectifiers.

The secondary is monitored by an HY510N integrated circuit, which is installed on a small daughterboard and provides under voltage (UVP) and over voltage (OVP) protections. Any other protection that this unit may have is implemented outside this integrated circuit.

Figure 13: Monitoring integrated circuit.

Most electrolytic capacitors from the secondary are from OST. Here is a smaller difference between CX400W and VX450W: VX450W uses Japanese caps here.