Huntkey Jumper 550 Power Supply Review

Secondary Analysis

This power supply has seven Schottky rectifiers on 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 two M6060P Schottky rectifiers connected in parallel, each one supporting up to 60 A (30 A per internal diode at 95° C, 0.64 V maximum voltage drop), giving 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 STPS30L45CT Schottky rectifiers connected in parallel, each one supporting up to 30 A (15 A per internal diode at 135° C, 0.74 V maximum voltage drop), giving 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 STPS30L45CW Schottky rectifiers, giving us a maximum theoretical current of 43 A or 141 W for the +3.3 V output.

The seventh rectifier, an STPS2045CT, is used by the +5VSB output.

It is always good to see the secondary highly overspec’ed like this.

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 13: +12 V, +5 V and +3.3 V rectifiers.

The outputs are monitored by the circuit shown in Figure 14. Its heart is a WT751002 integrated circuit, which supports only OVP (over voltage protection) and UVP (under voltage protection). The protection circuit, however, is complemented by two LM339 (quad differential comparators) and one LM393 (dual differential comparator) integrated circuits, which probably create the over current protection (OCP).

Figure 14: Monitoring circuit.

The electrolytic capacitors from the secondary are from Fcon.