Amacrox Free Style 85PLUS 650 W Power Supply Review

Secondary Analysis

Amacrox Free Style 85PLUS 650 W uses eight Schottky rectifiers on the secondary.

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 four SBR40U60CT Schottky rectifiers (40 A, 20 A per internal diode at 100° C, 0.60 V maximum voltage drop) connected in parallel, giving us a maximum theoretical current of 114 A or 1,371 W for the +12 V output. Talk about overspecification!

The +5 V output is produced by two SBR30U30CT Schottky rectifiers (30 A, 15 A per internal diode at 140° C, maximum forward voltage of 0.54 V) connected in parallel. This gives us a maximum theoretical current of 43 A or 214 W for the +5 V output.

The +3.3 V output is produced by another two SBR30U30CT Schottky rectifiers, giving us a maximum theoretical current of 43 A or 141 W for the +3.3 V output.

Figure 13: Rectifiers.

The secondary is monitored by two integrated circuits, a PS223, which supports OCP (over current protection), OVP (over voltage protection), UVP (under voltage protection) and OTP (over temperature protection, not implemented on this power supply), and a WT7518, which provides four individual over current sensors.

Figure 14: Monitoring circuit.

Electrolytic capacitors from the secondary are from Teapo and labeled at 105° C, as usual.