This power supply uses four 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 STPS30L60CW has its two internal diodes connected in parallel and is in charge of the direct rectification (30 A at 130º C, i.e. 15 A per internal diode), while one 40CPQ060 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 40 A (20 A per diode at 120º C). For our math we have to consider the part with the lower current limit, 30 A in our case. Applying the above formula gives us a maximum theoretical current of 43 A or 514 W for the +12 V output.

The +5 V output is produced by one STPS40L45CW Schottky rectifier, capable of delivering up to 40 A (20 A per internal diode at 130º C). This means the +5 V output has a maximum theoretical current of 29 A or 143 W.

The +3.3 V output is produced by another STPS40L45CW Schottky rectifier, which is capable of delivering up to 40 A (20 A per diode at 130º C), giving us a maximum theoretical current of 29 A or 94 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 outputs are monitored by a PS223 integrated circuit, which supports the following protections: over current (OCP), under voltage (UVP), over voltage (OVP) and over temperature (OTP, not implemented on this power supply). Any other protection that this unit may have is implemented outside this integrated circuit.

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Figure 13: Monitoring integrated circuit.

Most electrolytic capacitors from the secondary are also Japanese from Chemi-Con, but some models are from Teapo (Taiwanese company).