This power supply uses four Schottky rectifiers on its secondary. The problem is how they are connected. Instead of using the same design adopted by all current power supplies, the reviewed power supply uses an old design. To see the difference between them, take a look on the Secondary section from our Anatomy of Switching Power Supplies tutorial. This power supply secondary uses the design described as “A” on this tutorial, while almost all power supplies currently on the market uses the design described as “B”.

The +12 V output is produced by two STPS20S100CT Schottky rectifiers connected in parallel, which can deliver up to 20 A each (measured at 150º C), thus the maximum theoretical current the +12 V line can deliver is of 40 A, which equals to 480 W at 150º C. The maximum current this line can really deliver will depend on other components, especially the transformer, the coil, the capacitor and the wire gauge used.

The +5 V output is produced by one STPS30S45CW Schottky rectifier, which support up to 30 A (measured at 135º C). So the maximum theoretical power the +5 V output can deliver is of 150 W. Of course the maximum current (and thus power) this line can really deliver will depend on other components, especially the transformer, the coil, the capacitor and the wire gauge used, as mentioned before.

The +3.3 V output is produced by another STPS30S45CW Schottky rectifier, which support up to 30 A (measured at 140º C). So the maximum theoretical power the +3.3 V output can deliver is of 99 W. Of course the maximum current (and thus power) this line can really deliver will depend on other components, especially the transformer, the coil, the capacitor and the wire gauge used, as mentioned before.

Even though this power supply has a separated rectifier for the +3.3 V output, this rectifier is connected to the same transformer output as the +5 V line, so the maximum current +5 V and +3.3 V can pull together is limited by the transformer.

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Figure 12: The four Schottky rectifiers used on the secondary.

This power supply thermal sensor is located close to one of the ends of the secondary heatsink, as you can see on Figure 13. This sensor is used to control the fan speed according to the power supply internal temperature and also to shut it down if the power supply implements over temperature protection (OTP) – the majority of power supplies on the market, including the reviewed unit, don't have this protection.

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Figure 13: Thermal sensor.

On this power supply the big electrolytic capacitors from the voltage doubler are rated at 85º C (and manufactured by Teapo, a Taiwanese company), while the electrolytic capacitors from the secondary are rated at 105º C and coming from several vendors (Teapo, Fcon and KSC).