Ultra X4 500 W Power Supply Review

Secondary Analysis

This power supply has five Schottky rectifiers attached to its secondary heatsink.

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 40CPQ060 Schottky rectifiers, each one providing up to 40 A (20 A per internal diode at 120° C, maximum voltage drop of 0.68 V). This gives us a maximum theoretical current of 57 A or 686 W.

The +5 V output is produced by one STPS40L45CW Schottky rectifier (40 A, 20 A per internal diode at 130° C, maximum voltage drop of 0.49 V), giving us a maximum theoretical current of 29 A or 143 W for this output.

The +3.3 V output is produced by another STPS40L45CW Schottky rectifier, so the maximum theoretical power this output can deliver is of 94 W.

The fifth rectifier, an STPS20L60CT (20 A total, 10 A per diode at 140° C, maximum voltage drop of 0.56 V), is used by the standby (+5VSB) 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 outputs are monitored by a PS223 integrated circuit, which supports the following protections: over current (OCP), under voltage (UVP), over voltage (OVP) and over temperature (OTP, not implemented on this power supply). Any other protection that this unit may have is implemented outside this integrated circuit.

Figure 13: Monitoring circuit.

Electrolytic capacitors from the secondary are from Teapo and JinFu and labeled at 105° C.