This power supply uses a slightly different configuration from what we’ve seen to date, so we drew a simplified schematics of its secondary for a better understanding, see Figure 12.

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Figure 12: Cooler Master Real Power Pro 850 W secondary.

For the +5 V and +3.3 V outputs the two transformers are connected in parallel and each output uses two Schottky rectifiers in parallel each. Instead of sharing the same transformer output with the +5 V output, the +3.3 V line uses its own transformer output, which is great.

The +5 V output is produced by two STPS60L45CW Schottky rectifiers connected in parallel, which support up to 60 A (measured at 135º C) each. So the maximum theoretical power the +5 V output can deliver is of 600 W. This line is clearly overspec’ed. 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 other two STPS60L45CW Schottky rectifiers connected in parallel, which support up to 120 A (measured at 135º C) each. So the maximum theoretical power the +3.3 V output can deliver is of 792 W. This line is also clearly overspec’ed.

The +12 V output uses a very unique design, using three Schottky rectifiers and two IFRS3207 power MOSFET transistors. We thought that these three rectifiers would be connected in parallel, but this isn’t the case. Two of them are connected in parallel (four diodes in parallel) and rectifying the positive portion of the transformer output and one of them (two diodes in parallel) is rectifying the negative portion of the waveform. Take a look on Figure 12 for a clearer picture.

Three 40CPQ06 Schottky rectifiers are used, which can deliver up to 40 A (measured at 120º C) each. But, as mentioned, this power supply uses an uneven configuration, so the positive rectification (2 devices) can handle up to 80 A (960 W), while the negative rectification (1 device) can handle up to 40 A (480 W), for a total of 120 A or 1,440 W. This section is clearly overspec’ed, which is great.

The +12V filtering stage from this power supply is also different from other power supplies: it provides two separated filtering sections, one for the +12V1, +12V2 and +12V3 rails and another for the +12V4, +12V5 and +12V6 rails. This is great.

We could also clearly see that each virtual rail was really connected to the monitoring integrated circuit (a PS232S), which is in charge of the power supply protections, like OCP (over current protection). OCP was really activated, as we will talk about later.

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Figure 13: Transistor, two +12 V rectifiers, transistor, +5 V rectifier and +3.3 V rectifier.

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Figure 14: +3.3 V rectifier, +5 V rectifier and +12 V rectifier.

As you can see on Figure 14 this power supply has two thermal sensors attached to its secondary heatsink. One of them is used to control the fan speed according to the power supply internal temperature and the other is used on the power supply over temperature protection (OTP) circuit. We will talk more about this circuit later.

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Figure 15: PS232S monitoring integrated circuit.

On this power supply the big electrolytic capacitors from the active PFC circuit are Japanese from Chemi-Con and rated at 85º C, while the electrolytic capacitors from the secondary are Taiwanese from Teapo and rated at 105º C.