This power supply uses five Schottky rectifiers on its secondary.

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 rectifiers, however they are not connected in parallel. One FYPF2010DN has its two internal diodes connected in parallel and is in charge of the rectification (20 A at 105º C, i.e., 10 A per internal diode), while one STPS30H100CW has its two diodes connected in parallel and is in charge of the “freewheeling” portion of the rectification (i.e., discharging the coil). This device has a maximum current limit of 30 A (15 A per diode at 155º C). For our math we have to consider the part with the lower current limit, 20 A in our case. Applying the above formula gives us a maximum theoretical current of 29 A or 343 W for the +12 V output.

The +5 V output is produced by two STPS30L40CW Schottky rectifiers, each one capable of delivering up to 30 A (15 A per internal diode at 135º C). This means the +5 V output has a maximum theoretical current of 43 A or 214 W.

The +3.3 V output is produced by one MBR6045PT Schottky rectifier, which is capable of delivering up to 60 A (30 A per diode at 125º C), giving us a maximum theoretical current of 43 A or 141 W for the +3.3 V output.

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

This power supply uses a WT7517 monitoring integrated circuit, which is in charge of the power supply protections. It supports over voltage (OVP), under voltage (UVP) and over current (OCP) protections. OCP was really activated, as we will talk about later.

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Figure 13: Monitoring integrated circuit.

The electrolytic capacitors from the secondary are also from Teapo, with some models from Su’scon (both Taiwanese).