PowerColor Extreme 850 W Power Supply Review

Secondary Analysis

This power supply has six 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 uses four DSSK40-006 Schottky rectifiers (40 A, 20 A per internal diode at 130° C, maximum voltage drop of 0.60 V). Of the eight available diodes (two per rectifier pack), three are used for the direct rectification and five are used in for the “freewheeling” portion of the rectification. This configuration gives us a maximum theoretical current of 86 A or 1,029 W for the +12 V output.

The +5 V output uses one DSSK60-0045B Schottky rectifier (60 A, 30 A per internal diode at 120° C, maximum voltage drop of 0.68 V), giving us a maximum theoretical current of 43 A or 214 W for this output.

The +3.3 V output uses another DSSK60-0045B Schottky rectifier, giving us a maximum theoretical current of 43 A or 141 W for this output.

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

The secondary is monitored by a PS232S integrated circuit. This chip supports over voltage protection (OVP), under voltage protection (UVP), over temperature protection (OTP), and six over current protection (OCP) channels (four +12 V, one +5 V and one +3.3 V), matching the number of +12 V rails advertised by the manufacturer (four). We could clearly see shunts (current sensors) attached to each +12 V rail.

Figure 15: Monitoring circuit

All electrolytic capacitors used in this power supply are from Toshin Kogyo (TK, rebranded OST caps), and labeled at 105° C.