OCZ Fatal1ty 750 W Power Supply Review

Secondary Analysis

This power supply comes with eight 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 three MBR4045PT Schottky rectifiers, each one capable of delivering up to 40 A (20 A per internal diode at 125° C, 0.80 V maximum voltage drop). This gives us a maximum theoretical current of 86 A or 1,029 W for the +12 V output.

The +5 V output is produced by two PFR30L45CT Schottky rectifiers, each one capable of delivering up to 30 A (15 A per internal diode at 125° C, 0.52 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 produced by another two PFR30L45CT, giving us a maximum theoretical current of 43 A or 141 W for the +3.3 V output.

The eighth rectifier, an SR1045, is used by the +5VSB output.

Figure 13: Rectifiers.

This power supply uses a PS224 monitoring integrated circuit, which over voltage protection (OVP), under voltage protection (UVP) and four OCP (over current protection) channels, one for +3.3 V, one for +5 V, and two for +12 V. Additionally the monitoring circuit uses an LM393 integrated circuit (a dual voltage comparator) to expand the number of channels of the over current protection circuit.

Figure 14: Monitoring circuit.

Electrolytic capacitors from the secondary are also Japanese, from Chemi-Con and labeled at 105° C.