The secondary from Toughpower XT 750 W is different from the original Toughpower 750 W, however. Toughpower XT 750 W uses six Schottky rectifiers on its secondary, while the original Toughpower 750 W uses only four. The secondary from Toughpower XT 750 W provides a higher maximum theoretical current/power than the original Toughpower 750 W.

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 four STPS40L45CT Schottky rectifiers, each one supporting up to 40 A (20 A per internal diode at 130º C with a maximum voltage drop of 0.49 V). From the eight diodes available, three are used for the direct rectification and the other five are used for the “freewheeling” part of the rectification (i.e., discharge the coil). This gives us a maximum theoretical current of 86 A or 1,029 W for the +12 V output.

The +5 V output is produced by one STPS60L30CW Schottky rectifier, capable of handling up to 60 A (30 A per internal diode at 130º C, maximum voltage drop of 0.38 V). This gives 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 STPS60L30CW Schottky rectifier. This gives us a maximum theoretical current of 43 A or 141 W for the +3.3 V output.

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Figure 14: Rectifiers.

This power supply uses a PS229 monitoring integrated circuit, which is in charge of the power supply protections. Unfortunately there is no information about this circuit on the manufacturer’s website.

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Figure 15: Monitoring circuit.

Electrolytic capacitors from the secondary are also Japanese, from Chemi-Con and labeled at 105º C. This is an improvement over the original Toughpower, which uses Chinese caps.