Huntkey Green Star LW-6550SG has five Schottky rectifiers on its secondary, two for the +12 V output, one for the +5 V output and two for the +3.3 V output.

Since this power supply uses a half-bridge configuration to calculate the maximum theoretical current each output can deliver is easy: all we need to do is to add the maximum current supported by all diodes.

The +12 V output is produced by two STPS20S100CT Schottky rectifiers connected in parallel, each one capable of handling up to 20 A at 100º C (10 A per internal diode). So the maximum theoretical current the +12 V output from this power supply can deliver is of 40 A or 480 W. Of course this math is just an exercise and the actual limit depends on several other factors. It is important to note that this is the same configuration and rating used by Green Star 400 W and Green Star 450 W.

The +5 V output is produced by one S40D40C Schottky rectifier, which is capable of handling up to 40 A at 100º C (20 A per internal diode). So the maximum theoretical current the +5 V output from this power supply can deliver is of 40 A at 100º C or 200 W. This is a different component from the 400 W and 450 W models from Green Star series, which use a 30 A (150 W) rectifier.

The +3.3 V output is produced by two STPS2045CT Schottky rectifiers connected in parallel, which one capable of delivering up to 20 A at 155º C (10 A per internal diode). So the maximum theoretical current the +3.3 V output from this power supply can deliver is of 40 A at 155º C or 132 W. This is a different component from the 400 W and 450 W models from Green Star series, which use a 30 A (99 W) rectifier.

It is always good to remember that the real current/power limit for each output will depend on other factors, like the coils and the width of the printed circuit board traces.

As you can see, what Huntkey did to create their 550 W model was to increase the +5 V and +3.3 V rectifiers and the switching transistors. While replacing the switching transistors was an obvious move, Huntkey should have increased the rectifiers from the +12 V output, not from +5 V and +3.3 V. Nowadays computers consume more current/power from the +12 V line, as the CPU and the video cards are connected to this output, not from the +5 V and +3.3 V ones.

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Figure 12: The two +12 V rectifiers, the +5 V rectifier and one of the +3.3 V rectifiers (the other one is on the other side of the heatsink).

The secondary is monitored by an SG6105, which provides protections such as over voltage (OVP), under voltage (UVP), over power (OPP) and short-circuit (SCP). This integrated circuit is also a PWM controller, being in charge of the switching of the primary transistors.

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Figure 13: Monitoring integrated circuit.

In Figure 14, you can see the thermal sensor available below the secondary heatsink, in charge of changing the fan speed according to the power supply internal temperature.

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Figure 14: Thermal sensor.

The electrolytic capacitors from the secondary are from KSC, Teapo and Fcon and labeled at 105º C, as usual.