GlacialPower GP-AL650AA 650 W Power Supply Review

Secondary Analysis

GlacialPower GP-AL650AA uses six Schottky rectifiers on its secondary.

The maximum theoretical current each line can deliver is giv
en 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%. Of course the maximum current (and thus power) this line can really deliver will depend on other components, especially the coil.

+12 V rectification is done by two SBR40U60CT Schottky rectifiers, each one supporting up to 40 A (20 A per internal diode at 150° C), so we have a maximum theoretical current of 57 A (20 A x 2 / 0.70), which corresponds to 686 W.

The +5 V output is produced by two STPS30L30CT Schottky rectifiers, each one capable of handling up to 30 A (15 A per internal diode) at 140° C. This translates into a maximum theoretical current of 43 A or 214 W.

The other two Schottky rectifiers present are used to rectify the +3.3 V output, however they are not identical. For the direct rectification one STPS20L45CT is used (10 A per internal diode at 135° C), while for the “freewheel” diode one STPS30L30CT is used. For our calculations we have to consider only the diode used on the direct rectification, so the maximum theoretical current the +3.3 V output can deliver is 14 A or 47 W.

Figure 10: +3.3V, +5V and +12 V rectifiers.

The outputs are monitored by a WT7525 integrated circuit (not shown in Figure 11), which supports the following protections: over current (OCP), under voltage (UVP) and over voltage (OVP). Any other protection that this unit may have is implemented outside this integrated circuit.

Figure 11: Monitoring circuit.

The electrolytic capacitors from the secondary are also from OST, labeled at 105° C as usual.