Amacrox Free Earth 88PLUS 600 W Power Supply Review

Secondary Analysis

This power supply has eight Schottky rectifiers attached to the 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 generated using four SBR40S45CT Schottky rectifiers connected in parallel, each one having a current limit of 40 A (20 A per internal diode at 110° C, 0.55 V maximum voltage drop). This gives us a maximum theoretical current of 114 A or 1,371 W for the +12 V output.

The +5 V output is generated using two SBR30U30CT Schottky rectifiers connected in parallel, each one having a current limit of 30 A (15 A per internal diode at 150° C, 0.54 V maximum voltage drop). This gives us a maximum theoretical current of 43 A or 214 W for the +5 V output.

The +3.3 V output is generated using another two SBR30U30CT Schottky rectifiers connected in parallel. This gives us a maximum theoretical current of 43 A or 142 W for the +3.3 V output.

Of course these are all theoretical figures. The real current limits will depend on other components, especially on the coil used.

Figure 14: +12 V, +5 V and, +3.3 V rectifiers

The outputs are monitored by a PS223 integrated circuit. This circuit supports over voltage (OVP), under voltage (UVP), over temperature (OTP), and over current (OCP) protections. This circuit offers four over current protection channels (one for +3.3 V, one for +5 V, and two for +12 V). A WT7518D integrated circuit is used to expand the number of +12 V over current protection channels to four, matching the number of +12 V rails advertised by the manufacturer.

Figure 15: Monitoring circuit

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