Gigabyte Superb 550P Power Supply Review

Secondary Analysis

This power supply has six rectifiers on its secondary heatsink plus an LM7912 voltage regulator for its -12 V output.

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. As an exercise, we can consider a duty cycle of 30% for our calculations.

The +12 V output is produced by two SBR20100CT Schottky rectifiers connected in parallel, each one supporting up to 20 A (10 A per internal diode at 150° C, 0.82 V maximum voltage drop), giving us a maximum theoretical current of 29 A or 343 W for the +12 V output.

The +5 V output is produced by two STPS2045CT Schottky rectifiers connected in parallel, each one supporting up to 20 A (10 A per internal diode at 155° C, 0.84 V maximum voltage drop), giving us a maximum theoretical current of 29 A or 143 W for the +5 V output.

The +3.3 V output is produced by another two STPS2045CT Schottky rectifiers connected in parallel, giving us a maximum theoretical current of 29 A or 94 W for the +3.3 V 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 14: -12 V voltage regulator and +3.3 V, +5 V and +12 V rectifiers.

The outputs are monitored by a WT7527 integrated circuit, which supports over voltage (OVP), under voltage (UVP) and over current (OCP) protections. The OCP circuit from this chip provides four channels, monitoring +3.3 V, +5 V and two +12 V channels. An LM339 (quad voltage comparator) is also present on the solder side of the printed circuit board.

Figure 15: Monitoring integrated circuit.

Figure 16: Voltage comparator.

The electrolytic capacitors from the secondary are from Ltec.