Seventeam ST-380PAS Power Supply Review

Secondary Analysis

This power supply uses six Schottky rectifiers on its secondary and they are all from the same model: SBR30A60CT, each one capable of delivering up to 30 A (15 A per internal diode at 110° C). Each positive output uses two of these.

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%.

So the maximum theoretical current each output can deliver is of 43 A (15 A x 2 / 0.70), which translates into 514 W for +12 V, 214 W for +5 V and 141 W for +3.3 V. As you can see the secondary is highly overspec’ed, however we must remember that these are only theoretical numbers and the real limit depends on other factors, especially the coils used on the secondary.

Figure 13: Rectifiers.

The outputs are monitored by a WT7510 integrated circuit, which supports only under voltage (UVP) and over voltage (OVP) protections. Any other protection that this unit may have is implemented outside this integrated circuit.

Figure 14: Monitoring integrated circuit.

Electrolytic capacitors from the secondary are also manufactured by Samxon and labeled at 105° C.